Thanks.

if you take a look at physicsforums.com and physics.stackexchange and other various blogs, you will quickly realize the vast amount of knowledge he got.

Huh. I'm surprised, and I'll update.

Here is the disccussion I was referring to:

Let's see. He was saying that MWI made no ontological sense. I said something insulting (that's an ugly pattern- I don't do that to very many people on here), then Manfred started explaining MWI pretty well. I jumped back in to explain the Born probabilities as a consequence of it being a Hilbert space.

Then Mitchell correctly identified my explanation with a variant of Barbour's Platonia (I may have missed that on first reading) before launching into something like infinite-set atheism (that countable duplication of a configuration would count as an explanation of the Born probabilities, but that a vector in L^2 with a certain length would not). He also mentions that MWI has issues with relativity and preferred somehow; I admit I'm not qualified to talk about relativistic QM, so I can't counter the objection- but if it wasn't a problem for Feynman, I'm not especially worried.

...I should update again, because he did offer a decent restatement of my view before offering one criticism I understand (and reject as mathematical Ludditism) along with two that I don't have the background for. I think I've probably let my disgust over his philosophical stance on qualia bleed over into my estimation of his physics knowledge. Drat.

What do physics credentials have to do with this? Note MP's quote of Orthonormal's complaint in which he compared MP to Penrose!

I looked at physics stackexchange and quickly failed to change my impression of MP's grasp of physics. It's not terrible, but I don't see evidence that he can "do work." Given your interpretation of that thread you link, I shouldn't have bothered.