In effort to reply to main points I have to try to summarize them. I am attempting to do so accurately and not misrepresent you. Any mistakes made are honest ones.
Point one-Biden vilified his opponents when the chips were down after Iowa and it worked, so trying to immunize him against a similar strategy is unfair.
From the article linked the example of "sharpened attacks" on Buttigieg consisted of pointing out that at present his experience consists of being mayor in a moderate sized city. As you touched on, that can be called true, because it just flatly is. It is also not "vilification" in any sense of the word. I'd actually expect that Buttigieg would take it as encouragement to build his resume and try again.
I also don't see where Biden used any "red scare" attacks on Sanders. He was quoted talking about electability and how the GOP would use Sanders self identification as a socialist against not only Sanders but every Democrat down the ballot in November. Again, this can be called true because it just flatly is. Saying "if you hand them a club they will hit you with it" isn't vilifying. It isn't really even saying that the club is in itself a bad thing. It is just acknowledging the existence of the club and the reality that the opposition will use it if they have the chance.
Point two- the US electorate needs to get over the cold war and embrace the reality of socialism.
Probably so, but acknowledging the need does not justify a pretense that it has happened. The socialism "scare word" has and still does work in USian politics. It isn't "red scare" because clearly we have collectively relegated Russia into 'vanquished enemy' status and don't really worry all that much about 'a member of the US communist party is just a spy for the USSR.' What it is though is a widespread identification of socialist economic theory as 'failed.' Correctly or incorrectly, USians in the electorate predominantly attach 'socialism' as 'communism' as USSR and credit that economic theory as how the USSR lost the cold war. They are also constantly grasping onto every anecdote of a European country nationalizing anything and experiencing a bad consequence, and every anecdote where such nationalization "had to be given up as a failure." The only solution I see here is widespread education in economics applied over generations, not any sort of "embrace the self declared socialist and see if he can make a magical turnaround happen."
Point three- the pending revolt of disappointed youth.
It may very well seem like this is "right around the corner" and that these youth and their movement are so singularly put out and their issues so singularly critical that action to appease them has to be taken immediately before the whole place goes up in flames. I absolutely agreed with every word of that idea, and every argument presented in support of that idea. I hunkered down ready to eagerly support the pending revolution when it inevitably happened as a result of the pending irrefutable evidence that the electoral system was totally broken.
But somehow 1973 came and went and there was no youth revolution to be found. The person I heard those arguments from dropped out of the electorate in disgust, but showed less enthusiasm for an actual bloody revolution than I had. He reentered the electorate in the 90s as a Republican.
Conclusion...the guy on the street corner with the sandwich boards saying "the end is near" might be right. When the end does come there will undoubtedly have been one of those guys and we need to credit him for it. But there definitely will be one of those guys at the time because there always is, and all the rest of them will still have been wrong.
The thing about insults, or digs, or any kind of political grandstanding that involves taking shots at competitors or opponents, is of course they can also be factual. But them being factual doesn't negate them being used as vilification (which was the entire point, given the timings of the speech, in addition to it being a break from character in the primaries so far).
Insofar as using a "red scare" attack, anything that involves presenting socialism in a negative light
is that. It's exactly that. The GOP will use anything against any Democratic candidate - when people are criticising Biden's coherency? It's because the GOP will use that. Maybe the argument should be why offering up a socialist candidate as a label is better or worse than offering up someone who's coming across worse in a number of videos (in fairness, one of which I've seen edited, but a whole lot more I've seen haven't been) in terms of mental acumen and focus. Physical health is a big difference from mental health (I mean, in an ideal world, they'd all be taken as parts of a whole, but that's Another Derail and I don't want to inflict that on the thread. For better or worse, they're seen as disparate states and often attacked separately, or used in separate attacks).
"socialism ~= communism" is absolutely the problem here, as well as mainstream Democrats (not just Biden) playing up its weaknesses in general. We have that here too in the UK, when by comparison our centre-left candidate (who's more left-oriented than Sanders) barely qualifies as centre-left in a lot of European countries. For you, this means that Biden is a better chance, and he might well be for this election. But that association
needs to be broken - that's one of my central political beliefs in general. We have to remove the overtly conservative stigma around socialism as a concept and a label, and sure, like you said, that's going to take time. The problem here is twofold. Firstly, we're arguably running out of time. Secondly, increasing amounts of younger generations
are becoming more educated about it, and "waiting for everyone too firmly rooted in bias to die off" isn't really a feasible proposition. Moreso when you consider the fact that young people raised in conservative (or outright right-wing) families will also be growing up with bias inherited from their parents. It's not as simple as waiting for it to die out, and any educational reform in the States is going to come up against the entire problem that is the label in the first place. The dice are stacked against socialism, in a time when the failings of capitalism even in obvious examples like the poverty line, or the hourly wage rate, are becoming increasingly more obvious. Something needs to change. Maybe it isn't the United States of Socialist America, but hey. We can't keep on as we are.
It's very hard to accept a multi-generational educational plan when education is one of the hardest things to actually enact positive change for. Something
else needs to be done, arguably, which is why you see people getting into politics on these more leftist platforms (and again: only really very mildly leftist given the American skew on such labels).
r.e. the revolt of the youth. I didn't specify revolt. Any number of things could happen, from the gradual failings of real-life systems to an accelerated rate of pandemic events (not necessarily viral / bacterial, but localised / regional economic collapse, increasing precariousness for small and middle business chains, etc). It's a nebulous future, but the key thing I keep seeing is waiting for it to happen is really becoming an increasingly difficult thing to stomach. I'm pretty young, but I'm not
young anymore. I'm 30; I've had children. To me thinking 10 or 20 years in the future is
natural, and having lived through what I have, and seeing how these things are getting worse? "wait and see" is advice I find increasingly difficult to heed. I'm increasingly sympathetic to the need for radical change; perhaps you're not. Perhaps you are, but have accepted a longer timeline. I don't want to assume.
1973 is a long time ago now. A lot of things have changed, a lot of previously-considered fact has been superceded. I really urge you to listen to the guy on the street corner, because even if every time so far the theoretical hasn't happened,
it only needs to happen once. That's the problem with these kinds of theoretical situations, and the rationale about considering them dismissable (to whatever mild extent you are). It's not a matter of deciding who was right after the fact. It's dealing with the reality we find ourselves in. I don't
care who's right. I don't even
want to be right. I just want to see everything done by the people who have the power to do so to stop it. I'm not seeing that, on either side of the Atlantic, on any of the subjects I care about (which is, in general: minority rights, fossil fuels, climate change and labour law).