Because that was the quote implying that being cautious is an error if favorable outcomes are merely "likely".
I think you misunderstand in that case, I was suggesting delaying the first military unit does not mean you are an easy target. Most early game decisions are going to be of the reward/risk type given that the player will have very little information to base it on. You seem to be looking at opening moves as a zero sum problem.
I have experimented with early settler, early military and double scout openings and my current viewpoint is they can all be made to work as the game progresses. It is down to the player understanding what works as the game unfolds. Also you can just have bad luck regardless of your opening.
For example my current test game resulted in no envoys despite 2 scouts and finding 4 city states by turn 26.
I was surrounded by AI civs; Monty far to the west (although I met his scout on turn 14), Ghandi built a city 7 tiles away, Trajan 4 tiles away, Peter 7 tiles away, Pedro was away to the east. I met everyone by turn 34.
Trajan denounced me on turn 32 but that city was attacked by Peter so I joined in a couple of turns later (I had 1 warrior/3 slingers) - Peter would eventually capture the city so I had to take it away from him ...eventually and then start rolling on the city states. All this with no horses or iron (I didn't even build chariots until later and my play was very sub-optimal with regard to policies / city management).
I have had more sedate starts I can tell you
2 scouts using the warrior to chop barbs might be better for a no-conquest, happy-to-reload game.
You can still go conquest with a 2 scout opening of course, I found the above quite fun ... especially the 1v1v1 fight right next to my capital. And no I didn't re-load, I just rolled with it to see how it went.
Unless someone can build an empirical argument showing that 2 scouts > 2 slingers or vice versa regardless of those factors it's not likely to be settled quickly.
I hope there is no right way to open, we wouldn't have anything to discuss if that was the case.