There's definitely a ton of personal vendetta in there, but nothing he said was wrong either way. It's the delivery method that people are taking issue with, and many people are contorting that into "Leffen isn't bad because of this video"
Edit: The shirt shit is a huge stretch, though.
I'm not sure if you even watched the doc, and if you didn't I can't blame you at all because it's two hours of bullshit you probably already heard about. But it goes far, far beyond Hax bringing up the ordinary complaints the community's had against Leffen for years.
* Hax claims Leffen has taken control over the entire Melee community through manipulation and subterfuge and is turning it into a dystopian society ala 1984.
* Hax uses multiple examples of Leffen being "evil" by citing forum posts when he was a teenager saying milquetoast edgy nonsense
* Hax claims the arguments he had with Leffen when he was 15 gave him post-traumatic stress disorder.
* Hax claims Leffen has a "Dark Triad" (a bumbling misuse of the term) and is objectively a psychopath, narcacist and a machiavellian
* Hax describes an incident where he chased Leffen around the hallways of a covention screaming at him when he was not responding and trying to get away.
* Hax goes into great detail about how Leffen tried to "ruin" his controller by saying he thinks L and R should be swapped, and how arguing on discord caused his friend to ragequit the Melee community
* Hax quotes
David Icke and uses his concept of "Tip-Toe Totalitarianism" to describe Leffen.
I haven't even gotten through the whole thing, this is just the shit I remember.
EDIT: Oh, and I forgot to add that he's said:
* Blocking people on Twitter should be illegal.
* Not allowing people to mob you on Twitter is a manipulation tactic
* "Manipulating language" should be illegal
* Leffen should be in jail for being mean