As far as I understand, every user must know the trust network of all other users, which 1) doesn't scale much 2) has terrible privacy implications.
I can imagine this being reduced by at least a factor of 10 without much impact on the trust score. But note the “random subset” means different people will have different trust scores for the same peer :shrug:
For (2) yeah we probably need to lower our expectations on privacy for the time being; it’s a masters thesis and privacy in open distributed systems is very tricky.
If we do care about privacy, any moderation system should first be designed to meet that goal. Its not worth designing a moderation system if we don't first know it will work with one of the core requirements.