I think that is a fine stand for our site.
Because we are a small site, with probably one moderator per new question per day, statistically speaking. And because of that, every question and every answer is under a microscope. We have, if I may say so, a very high "experts-to-clueless people" rate. If we see an AI post, it smells like AI and it's pointless. Everyone can read and see for themselves. Joe Random can see, that it is a generic non-answer. And (down)vote accordingly.
On our site, there is also no incentive to cheat. If you get green internet point here... the world doesn't care. Matter of fact, I may not want my next boss to know beforehand, that I know my rights given to me by our labor laws.
Stack Overflow has 4 questions per minute. Not per day, on a good day. And they have a huuuuge amount of basically clueless people looking for help. And you cannot tell if an AI post is correct. The AI will lie to you. The official term is "hallucinate". Because AIs don't lie. But they flat out answer something that is not true. And a normal pass-by reader will not know. It takes an expert, a seriously dedicated person in that little corner of knowledge to say "wait, this is wrong". Their voice will drown in the noise of "oh, this looks correct, it's nicely formatted and pleasantly written". In a way, it is worse than spam. Because spam is something we all have been trained to read around. It's just noise, we deal with it daily. AI generated answers are not noise. They look like signal. Until they lie to you. And you won't even know, until you try that answer for yourself.
Stack Overflow green internet points are also perceived in many regions as something helping you to get a good job and therfore a good life. That is a big incentive for cheating.
So Stack Overflow has a higher incentive to cheat, less rigid user feedback for cheaters and not enough moderators per question to make a difference with just a friendly comment. They will be flooded with bogus content if we open the flood gates.
So as a moderator here, I could shrug and just say "doesn't concern me really". That is why I was undecided at first.
But I am a user of Stack Overflow. And I don't want that to go down in flames. The decision itself is wrong. And for me, not feeling it here, doesn't make it less wrong.