There's a difference between finding it challenging to fit in and being a bully though, and let's try not to collapse that.
Was Felleisen's behaviour a "deliberate misuse of power... that intends to cause physical, social and/or psychological harm"? I don't know this guy personally and all I've read is some stories about him on these blog posts, but I'm not sure if he was deliberately intending to hurt other people, or merely doing so inadvertently out of social incompetence, deficits in cognitive empathy, emotional dysregulation, theory of mind deficits, difficulties in perspective-taking, etc? Individuals with neurodevelopmental and other psychiatric disorders can sometimes exhibit all of those inadvertent sources of interpersonal harm. (I'm not saying Felleisen has any such disorder – maybe he does, maybe he doesn't, I have no idea, so I must assume he might.)
[0] https://www.ncab.org.au/bullying-advice/bullying-for-parents...
Ultimately even if you actually could not act any differently because of a disorder, others would still not be required to tolerate you. This is a consequence of being social animals, we set expectations for behavior and we enforce them. If you can’t play the game, you can’t exactly expect people who can to stop playing for your sake.
Why are intentions irrelevant? If someone is hurting me (or others), I do consider the question of whether they are doing so intentionally or inadvertently to be highly relevant to my judgement of their behaviour and how I am going to respond to it.
If a person bullies because they have some kind of social ineptitude that makes them not realize they were bullying. That person is still a bully. However, its important to recognize if this was the case because the alternative is that he knew better and did it anyways because he knew he could get away with it.