I'm trying to keep in mind this isn't something you approached as a product to release or anything, and you're a student. I feel like I'm coming off pretty harshly here, but... you should be more worried about the "nefarious purposes" part than anything else, right now. I feel like offering this sort of service publicly - particularly in 2025 - requires some legal counsel.

One other concern about the implementation: it sounds like Hub administrators - who is just the first person to create a Hub in a particular area - are given a lot of power. No more Hubs are able to be created in an area? So if a Hub admin abuses their power that area is screwed, unless of course you (or whoever would be handling such cases, if indeed that would happen) agreed that they've overstepped, which may or may not be the case, particularly with a vague TOS

Anyway I think the idea is intriguing, and like new ways of exploring social media/communities.