It is valid. It's a game. To say that the mindset "It's not if you win or lose its how you play the game" is not valid shows that you should be offending yourself then by imposing your view of how to play on others. As you are imposing the mindset in your post that it IS if you win or lose that matters not how you play the game; which is pervasive. Get over yourself.
He didn't convey his point very well, but it is quite valid. The issue is not when someone does not play to win, but rather when people who have mental blocks against playing to win argue against the validity/fairness of those who do.
My experience is a little different from his. As a good player in games of the past, I am used to getting dogpiled (very common for 3 people to gang up on me in mario kart back in the dorm days). I would *much* prefer that they do that rather than saying I'm so good I can't play (which would be so lame that the only way to make it worse would be to introduce a pretend excuse with that as the real reason). Rather, if they did *not* dogpile me, they had no realistic chance and they knew it. Which way optimizes their chances to win? If someone playing with them refused to do that, then the person who would eat complaints was *me*, because some slime bucket utilizing made-up rules wouldn't cooperate with the other players (this slime bucket was usually the greatest offender of complaints). He wanted it both ways ---> use and even impose made up rules but still win. This came close to getting me punted out of the playing rotation despite the fact that I was actually playing by the rules and *not* doing anything perceived as cheap!
Of course I did like some reasonably dirty tactics, like throwing fireballs or pikachu's thunder across the map to damage people w/o risk in smash brothers. I was #2 in that game at first on my floor (eventually getting good enough to beat the #1 guy straight up), but the whining over my tactic was IMMENSE. Why? Because it was perceived as cheap. The guys below me hated it, and would on occasion threaten to not even play if I did it. The #1 hated it too, but he didn't complain. His reason for hating it was that it lowered the chances for him to win, and thus he rather sensibly targeted me

...but only when doing so was advantageous for him. Those 1 on 1 fights and the judgment to engage them were part of the reason I was able to get better and skill in that game got *quite* lopsided, as it seemed like we were the only 2 people who actually improved.
Interestingly enough, I learned a thing or two over the years about human dogpiling in gaming. The way to play out of that position is to create incentive for the other players to abandon their alliance sooner...that is to say after I'm gone one of them would have to win, and so each of them will want to betray the others just a little bit sooner so that they have the leg up after I'm gone (thus they might turn-coat after I'm weakened or in rare cases even before). This is essentially the only way to force equilibrium between skill disparity ----> I certainly lost sometimes, but still won often enough, and that was true of the dogpilers too. The slime bucket was the big problem in that play group, whining all the way through. Fortunately, the others were too mature to fall into that pace and he wound up being the one that virtually always lost (dying first meant giving up the controller). Oddly enough, I had some incentive to *not* target him because he sucked and leaving him in increased my odds of not dying first.
Anyway, I could cry "cheating" on their ganging up all day and so could anyone else, but it isn't and artificially pushing pretend rules would make the game less dynamic. There's no room for opinion on this...there are things that violate rules and things that do not. Things that do not are not cheating. Find something else to call them.
Artificial rules in this sense are a problem in civ because 1) players who use them improve more slowly and 2) if people successfully impose them on others, they can actively inhibit progress.
Even that's fine if it does in fact make the game more fun to people...but misleading people as to what is and is not cheating is another matter.