That still makes no sense

I don't think that's the reason. The code mentions it filtering out "low-effort" communities so the devs probably didn't like seeing so many posts from it on their frontpage.

# sort out the 'seven things you can't say on tv' names (cursewords), plus some
# "low effort" communities

You're wrong. Rimu has never expressed any objection to pro-LGBT sentiment and has even done interviews in regards to that. I have seen him ban people for anti-LGBT bigotry. This particular ruleset looks like a copy and paste from the retention rules that piefed.social currently has that doesn't save data from communities after 6 months. (RImu doesn't have a high opinion of meme-themed content and believes it to be a drain on server storage).

I agree all of it should be optional, and I believe it currently is anyway as instance owners can revert this.