I would also like to know

type "amethyst censorship" into primal search and see what hes been saying.

One thing I have seen is that some of his posts were deemed as spam for consistently promoting something. He was using the same message over and over. With what frequency I dont know.

its something like: there's an algorithm in amethyst that auto mutes accounts if a group of the people you follow have muted them

from memory it initially wasn't very transparent but now there's a setting where you can see

something like that , things change so much here though, so don't quote me