Call his ass up and give eem an earfull on why you don't buy his Volume parameter.
You know you "can't argue with idiots". They will drag you down to their level and then beat you with experience.
I wouldn't care to argue against "holy grail conventional wisdom". No win in that. I can't even convince you, so how could I convince a big profile person like him?
You don't need to "take anybody's word for it". (You should take mine because, well, I'm me.
) But you could do your own study. It would be a tedious chore, but you've have to keep a log of the results from "all the trades I took where I considered volume" and compared that to those same chart setups where you ignored volume. That's a lot of work. Few would do it.