I'd guess that whatever value is derived by arguing over whether someone is racist or sexist can be produced better by tabooing those words, and arguing more specifically over what the specific claim is ("would his words be offensive to a significant number of member of such group" "is he trying to increase his own group's relative power/privilege over the other group", "does he believe in an innate inferior moral worth for that group", etc, etc)

I notice a glaring omission from your list of questions. Namely "are his words if interpreted as a factual claim and/or argument true and/or valid"