There's people actively advocating for a no fly zone, not sure why you're acting like it's a distant possibility.

Biden and NATO are opposed to it because it goes against their own interests, mostly. The popular opinion likely won't matter, as it often doesn't in politics and some of the proposals have been fantastical, such as a 'non-kinetic no-fly zone' being operated from space.

A no-fly zone goes against long standing thinking in nuclear deterrence, which is the basis on which NATO was originally found upon. NATO didn't think that they could win a conventional war against Soviet Union (and the position of West Germany strategically fragile in such a conflict), which lead to a lot of theorizing on the use of nuclear deterrence instead. To enforce a no-fly zone, NATO needs to destroy antiair weaponry in Belarus and Russia (to keep its own air superiority in tact), but from a Russian point of view, it's impossible to distinguish between conventional and nuclear payloads and both them and the US has not disavowed the option to use first nuclear strikes, for strategic nuclear deterrence reasons. To this day, Russia still has a fail-deadly system known as Perimeter in place. The potential price of escalation is thus high.

I have seen exactly one person argue that the risk of nuclear war is no barrier for establishing a no-fly zone, but I can't imagine Biden or NATO leadership willingly sacrificing themselves to the Ukrainian cause.

There's nothing in that thread that disagrees with that anarchist statement.

I praised them for their moral clarity. That is, I found the DSA IC to be muddled in comparison and too close to sitting by sidelines. Appeals to hypocrisy just can't hold candle to the light of principles.

Not really sure what you're going so hard in here for

I was mostly just ranting myself, thus I kept myself from positive proposals and I didn't want to spent effort into debunking either. If I was writing a serious piece, I'd discard the OP as my first draft and write a couple more before starting to polish it up.