This is so wild- I'm legitimately here because I just watched the same video and wanted to see if Kagi could do something about this as well. I think at the end of the day, there will be no "solution" against this, but I think there are ways it can be mitigated.
My thought was, what if a "moderation lists" feature like what Bluesky has was implemented? Or something like that- something community built. Maybe there could be a few community-contributed lists that are specifically for things like the AI slop sites. At that point they could even work for other content people may want to avoid. Contributing to the list (like, voting a website as bad) could lower the result of that website in the list for everyone who uses it.
I think these websites try and cover so many bases that it would actually make this method effective. It wouldn't be reliant on everyone searching the same thing. Hit from all sides in a way.