Give a broad solution to this problem:
RACIST joins fediverse site A.
Does a racism against an innocent Fedizen.
Site A bans RACIST.
RACIST joins fediverse site B.
Does a racism against the same innocent Fedizen.
Site B bans RACIST.
RACIST joins fediverse site C.
Does a racism against the same innocent Fedizen.
Site C bans RACIST.
Et cetera for the thousands of Fediverse sites.
This assumes that all Fediverse sites would ban someone over racism. And that RACIST doesn't start their own Fediverse site. And...