Why would you refuse the other side of the story? The OP posted first so he is more correct? I don't think that's how things work. The first to speak isn't the most accurate. There are two sides to every story, and In this case the other side is that the OP was argumentative and caused issues between members. Honestly, I find that more realistic than him being treated with prejudice for his disability since those kinds of interpersonal problems happen in groups all the time.
And to be clear. There is NO REASONS AT ALL to accommodate someone who is argumentative, causes problems in the group, and in general brings moral down. None at all. You can gladly play with someone for 6+ dedicated hours a week that you can't stand all you want. Good for you that you have that level of patience. However, there is no reason that anyone should be expected to put up with an attitude like that for hours each week for months on end. None. Also you said they never explained what was so argumentative. Did you ignore the part of the post where that guy explicitly said he didn't think the discussion belonged on the forums and was willing to talk to the OP directly in game? It isn't for us to know because it's not their job to lay their dirty laundry out for all of us to see and judge them. You should know that already. This probably wasn't due to mistakes or a lack of understanding or even a lack of compassion and forgiveness. Toxic elements should be removed from a raid because you will literally spend dozens to 100+ hours in dungeons with these people. You have the right, nay the duty, to ensure you play in an environment that is both fun and stress free. I am not, and others are not, social care givers here to put up with toxic attitudes with the goal of turning a frown upside down. We are here to win the fight and try to have fun all after a long day of work, raising kids, etc. Not for me to come home and put up with some toxic little punk attitude. I'd rather kick them and get someone who is a poorer player with a better attitude every day of the week.
You argue always for people to be more accommodating. Why can't the little punk players who have poor attitudes learn to accommodate the other people? Why is it always the little man who must be treated so much better than everyone else regardless of what his attitude is? Just because he was the minority does not automatically make him a damsel in distress. Sometimes that 1 person was the problem all along. You clearly always pick the underdog in these arguments, but to do so and always protect that person is a fallacy. You're assuming they needed the protection and that they weren't at fault. You literally know nothing about them.