bad actors can spam disgusting shit all over the damn place to the point where one relatively large community (I believe it was c/shitposting on Lemmy. world but I can't remember for sure had to be shut down by the mods for a while because it was being bombarded by CSAM.
I guess he hasn't heard of, I think it was r/AHS, that did exactly this routinely to get subreddits they didn't like shut down.