He is actually really good. By far the best on YouTube. The quality is so high (because it's based on technical reports), you can learn something from it as a professional engineer.
MentourPilot is not exactly the only YouTuber going off of actual technical reports, and I did not question his accuracy — I said I find him "grating". I'd rather watch old Mayday episodes than MentourPilot — Greg Feith, for one, is a great communicator. John Cox, too.
I find his content over-produced. As in, he puts too much effort into the production instead of just dispensing the information. I like Kelsey from 74-Gear and Juan Browne for their down to earth delivery. But that's what makes YouTube great having so many choices.
I really don't know what you are talking about.