It's not illegal, but it's still weird, creepy and potentially harmful and no
amount of lambasting about "the problematic age gap discourse" will make it not
true.
Neither, really. They were banned for "sustained hostility," a fair bit after that big thread where they got dogpiled. They got into the mindset of "me against the site" and got really combative over every little thing, always looking to pick fights and push contentious angles. I had a bit more sympathy for them than most, but at a certain point getting them off the site was probably better for them.
The final straw was that they started going around saying stuff like: "he/him, man detected, opinion discarded," but it was really more about the sustained hostility.