It seems to me that Mr. McGrew is demonstrating incredible internal strength: He is resolved. He is unswayed by people who are dropping in to tell him he is arguing incorrectly. He is not distracted by people telling him to go elsewhere. He is not terribly affected by individuals shifting the context and meanings of statements. He is arguably holding his center without being drawn out by red herrings or falling into black holes. It seems that he is defining the ground where others meet him. Moreover, he does not appear to bind himself to "winning" within typical (perceived) aikido rules of engagement.
Still, people feel they must engage him, attack him, prove something, hit him with the ad hom. attacks, ... and there he stands.
The same could be said of a 6-year-old with his fingers in his ears saying "La la la la la la I can't hear you."