The Free Radical policy on harassment is pretty simple: I will not allow anyone – local or federated – to let a guest feel unsafe. This is my living room and no one can come here and harass my friends. My general guideline is to take the minimum action necessary to address a problem. If a guest can themselves silence an annoying person and that fixes it, awesome. If the problem escalates and requires dropping the banhammer on a whole instance, then so be it.