Stallman was defending a friend and, by my reading, logically correct in the narrow point he was making. Anyone can sympathize with those priorities. However, he chose to place them above social realpolitik like "don't touch sufficiently radioactive subjects" and "almost nobody has time to dissect your argument so you'll win or lose the optics game on fuzzy associations alone." To be principled in this matter was to be antisocial. Most of us, myself included, would drop the principles in order to get along with everyone else, but that's not how Stallman rolled.