Menachem, what Neville is saying is that a rabbis name attached to something isn’t a defense thereof if the rabbi is a member of the movement in question. He’s saying that we shouldn’t just accept it as having rabbinic approval if the rabbi himself is from that sect.
He’s also going against the idea of the Lubavitcher rebbe being right because he said he’s right. Something some Lubavitchers have an issue with