One can never be sure, and that was speculation and opinion.
That creator has one follower and the game has no tags... If no one reports things, things tend to stay up, regardless, if an admin would de-index it, or not. If that is indeed the reason for the de-indexing. I doubt that the image itself would be reason enough, if there was content reasons.
My stance is, if we allow games where you can kill people (practically all ego shooters) it is quite established that not even criminal things in real life concern the content of games. Games are supposed to allow to do things that you cannot in real life. Like fly. Go on adventures. Be a hero. Or a villain. Whatever.
But that does not mean, that itch has to passively promote anything that comes along. I know of a creator that got deindexed for lots of low effort projects. (At least I assume that is the reason. One can never be sure)
It is frustrating to not know the reasons, but I can think of reasons why they do not tell, as I described.