Firstly, I think you are grossly oversimplifying his position. Secondly, I have no reason to think someone arguing the opposite position from me is a heel.* Nor should you.
*= Let me admit right here, right now that I'm a lawyer and an Internet message board is not usually a place where I look to impose rigorous critical standards when it comes to evaluating arguments. That's what I do in my day job.
That being said ...
When it comes to evaluating pro wrestling, of course you have to look at the footage - that's the evidence in chief, as it were, which is recorded output - but then of course you have to then evaluate said evidence. That's where you get subjectivity from the observer. Grimmas is (as I see it) legitimately reaching a different conclusion than you are when comparing two wrestlers who by most rank in the top 99.9% of all pro wrestlers, ever. Surely it's not inconceivable for someone to reach a conclusion that by their own criteria rank Bret Hart higher than another great worker because of various features of his matches (output) and the demonstration of wrestling skills that he values more highly than you do (input).