Help me figure out if I am ableist towards possibly autistic colleague

This is long I am so sorry.

I am not perfect and this has been quite a journey. I have a colleague I assume is autistic and comoletely non masking. I also assume this may be disclosed to the management (based on accommodations he is given and their awkwardness in dealing with him) but it is not disclosed to colleagues and external collaborators such as myself. A lot of people know I am audhd in that office but not him.

I try to correct misinformation in the office and validate his lack of eye contact, small talk, or acknowledgment of other people saying hi, or aversion to the stimulation of an open plan office, with an open plan kitchen (he is the only non management person that has his own office).

However I think there is an issue that exceeds autistic symptoms and I have been feeling both conflicted and guilty about resenting him.

One point of contention for instance (likely) is veganism. He he has told us he is vegan, not that others eating or microwaving meat dishes in the common kitchen bothers him, but judging from the poignant door slamming, he is feeling angry he has to deal with it. I hardly eat at the office and prefer sandwiches etc. but have been indirectly accused along with everyone else of not supporting his organising a vegan festival (not work related). We have never had a conversation or even a positive work interaction.

This is my big problem. He refuses to speak to me whatsoever unless it is absolutely necessary. Occasionally he does not reply to other coworkers as well but other times he will have no trouble expressing his opinion, think IT but only willingly providing solutions for one software, the rest of the issues are met with annoyance.

It happened again today. I knocked, entered and said hello with no response but that is no problem. Then I make the request, explaining the deadlines and the things we can be flexible on looking to accommodate his schedule into this unexpected task. Now the reason I do this in person, other than that I have not been requested to send over things in writing instead, is that when I do email, there is no response to my questions, I get a simple ok and when we need to actually do the work all sorts of unadressed issues come up and I usually have to involve other colleagues to find fast solutions and workarounds.

At the end of my request I was dismissed by a hand gesture without any other acknowledgment. I left without addressing his behavior but I did say that if this the case when he gets my input in email he must immediately act (removing all the flexibility options). I feel awkward about going to management about this but at this point I actively avoid handing out tasks to him.

I don't want to cause issues and judge too harshly but needs are not communicated and every attempt to find communication and collaboration methods is met with what I perceive as hostility. Am I being an A-hole? Is this just communication impairment? Can I find a way to better communicate and if yes should I or would I be a pushover? I am really confused.