The games got listed again, after 2 days. That is actually pretty fast. I still don't know why they were delisted, and I'll probably never know for sure.
Reasons to be quarantined and un-quarantined are intentionally kept secret. It is an attempt to not give the malware uploaders a blue print on how to avoid getting quarantined.
If I were Itch, I woud even add randomness in some way to that system, just like it is supposed to be on airport security ;-)
I am not sure if banning those spambots does anything. I do not see them repeating comments on the same game. Usually it spams hundreds of games in a few days. Itch should tackle that somehow, but it might take a while.
There was one particular scam they managed to shut down a few years ago, but even that was going on for quite some time, till they came up with a method to a) deal with that and b) not completely change Itch by doing so. (It was fake download buttons. The reason you see a red outline around external links is that. After they changed that, I never ever saw a fake download button on Itch)