Though I do have to wonder: if intra-left sectarian invective is to be considered unacceptable, does that include a Trotskyist posting something like "social democracy is a disease"The unwritten rules say that someone MORE radical can feel free to criticize or mock someone LESS radical, but not the other way around.
This is why, when some testosterone-head in a hoodie plays smashy-smashy at a demonstration, it's not OK to question his "diversity of tactics", but the next day, when the tear gas is out of everyone's nostrils, it's perfectly OK for him to describe peaceful protesters as "marching impotently on their knees".
Well, setting aside my example, the original point was that we shouldn't use "Trotskyite" because it's the term of abuse by Stalinists against the followers of Trotsky, and is thus offensive to them.
I'm not sure who would be considered more radical for the purposes of your "unwritten rule" there. Both factions in that debate seem to regard the other as being fake revolutionaries, if not outright reactionaries(I've heard Stalinists call Trotskyists agents of US imperialism, and of course the Trotskyist viewpoint on Uncle Joe is well-known).