How about a rating system for people? And each rating could also be biased by the rating of the person giving the rating. Kind of like pagerank for people. Then the posts of those who have the most positive ratings float to the top of the stream.
Sure trolls will support other trolls but I'm pretty convinced most people are good people and should easily outnumber and be able to take down gangs of trolls online.
This way the community self moderates and is able to weed out the undesirables and assholes on the platform all by themself, no intervention required.
The people you rated highly could also float to the top of your stream so if you enjoy the trash talking of milo or similar characters you can still see them without them poisoning the well for everyone else.