That's still ad hominem. You are dismissing everything he is saying and justifying it with a character assassination. That is the dictionary definition of ad hominem, and it is intellectually dishonest.
He hyperbolously used the term "hivemind," but even after rewatching the ending, there's no mention of a hugbox, nor any condemnation of the concept of a fandom in general. What he mentioned was referencing an overtone and a trend in the brony community, not a totality. I feel you are grievously and maliciously misinterpreting what he said.
First, if it was his honest experience with the fandom, then it isn't foolish for him to bring it up.
Second, he distinguished the difference between his issues with the fandom and his issues with the show, and applies them appropriately to his enjoyment of both. He does not enjoy the show because its quality has declined; and he does not enjoy the fandom because he has had terrible experiences with it. This has absolutely nothing to do with scapegoating, which is the practice of singling out a specific party to hold the blame for things that do not involve them.
Third, that isn't what Godwin's law even states. Godwin's law refers to overused and hyperbolic comparisons played for emotional appeal. Ironically, your comparison might be an invocation of it, in some way.
You are cherry-picking and you are strawmanning. You are looking for excuses to dismiss the parts which do not conform to your view, and hyping up the parts that (taken out of context) do. Despite his explicitly stating that he acknowledges both the good and bad experiences he has had with the fandom, and both the good and bad individuals he has interacted with, you still assert that he attempted to demonize the entirety of the fandom. You are creating a fake Tommy Oliver to burn in a court of public opinion, instead of addressing the complaints made by the real Tommy Oliver.
His criticisms, when taken in a general sense, are very true. There is a large, loud faction of the brony fanbase which acts exactly as he describes. Tommy is not "of questionable character" for pointing this out. If anything, I am starting to question your character for attempting to defame him like this.