The problem is what differentiates a real user from a bot. No WoT algorithm can solve for the lack of that difference if it exists.

You definitely can't filter out all bots. Some users even explicitly care to interact/follow bots. You can, however, filter on credibility. But like irl social credibility, there are different interactions you can work with to establish it. It can be context dependent, but i think even some sort of random rotation between them would be effective. I don't have evidence, for these claims but I think it would be something interesting to play around with, especially in a space where so many are searching for "the best wot algorithm"