I can't speak for your H, but if it was me, the confrontation would be a bad idea. I do believe that confrontation would work quite well in many cases, just not with me.
It's hard for to even imagine choosing mb over ML with a willing W, but I'm trying. To my way of thinking, if I had a willing W and was still using porn and mb’ing and keeping it from her, it would be something I didn’t want her to know about. Pulling it out and waving it in my face would just make me mad – and even more secretive in the future.
It’s also hard for me to imagine having a W who wanted to ML and turning her down, but I’m trying here too. I’m trying to imagine that I have sexual desire (thus the porn) but for some reason, don’t want to ML with my W. In my own particular case, the only reason that would happen would be if there was some BIG problem in the R. The best hope W would have would be to continue to let me know that she was both available and even eager, and to look for the elephant in the room. Of course in my case, I would be very eager to acknowledge the elephant, fix things, and ML with her. So all of my advice is probably worthless.