I tend to think that AI-generated content by itself is not a problem for SN.
That's because (unlike one other notorious website), "upvoting" content has a cost. We will send sats towards valuable posts and they will naturally rise above the noise.
And if someone finds particular content worthy for them, does it really matter who or what created it? (That's the "big question" for humanity to answer.)
What we should stop doing is zapping with trivial amounts (like 10 sats) everything that looks like good content (just because it's proper English and long form) and only zap things that we find individually valuable.
Now, there is a potential problem of bots manipulating the system to promote its own garbage. But maybe it's not a problem, after all SN allows you to boost your own content, and as far as I know, having multiple accounts is also acceptable - we trust that the money signal sorts out value from chaff.