I agree with your feelings on the biggest issue with a No-Fly zone, not to mention that from what I've heard and read, it would have a very limited impact on the situation on the ground. So the risk/reward isn't there.Ah, the ol' "just a message board" line. I know, I said it originally that none of us, including myself, know what we're talking about.
My disagreement is your continued misrepresentation of my position, saying (paraphrasing) that I'm scared for the US to get involved because I think a nuclear strike is a "foregone conclusion" or even likely. I've said, multiple times now, that I very seriously doubt it would happen. But I don't know that to be 100%, and apparently neither do the people involved in this who's opinions actually matter. You know, the US administration and NATO.
Getting in a direct hot war with Russia, even just by enforcing a no fly zone (aka, shooting down Russian aircraft), is only going to rally support at home for him, as the US/NATO will likely be seen as the aggressor to them, even though we're not. Maybe that emboldens him and a few of his underlings to escalate things.
However, I think Putin using nuclear weapons in a direct engagement with the US is almost guaranteed. Maybe not if the fighting is limited to just Ukraine, but if the US were serious about it, they would go after Russia's ability to conduct war. From what I've seen of Russian military defenses, the US might be able to virtually incapacitate Russia's ability to do this in less than a month with conventional weapons alone. Feeling cornered, Putin would go to nukes. If anything because he'd rather end civilization than be forced to admit he lost something. He is just like Donald Trump, only a little bit smarter. If it weren't for Trump, he would have the most fragile ego on the planet.