You see Nathan wire walk pretty competently throughout the episode without the mask, so I don't understand why he wouldn't just do it himself at the end. I definitely wouldn't say it was "probable" that he didn't do the walk himself- I can't imagine what the benefit would be.

Why is this reviewer so focused on the viability of the business idea in practice? He's missing the point of the show. Where's John Teti??

Agreed. B+ grade is a joke!