This isn't ad hominem. He is not saying "I don't care what point you are making because you are trash", he is saying "you do not understand what you are doing well enough to accurately make the assertions you are making". It is not ad hominem to not give a job as a statistician to someone who flunked maths.
He also does not ever state that he himself does. He stated that there are many veteran players, high level players, testers and content creators who understand the game and how it is played exceptionally well who consider this patch to be a total garbage fire.