His being more anxious because he was disabled is IMO simply nonsense and plays to the minds of us seeing disabled people as sweet, harmless or less than human.
It bothers me for a number of reasons which I struggled to express yesterday.
If his defence is 'like most disabled people, I am much more likely to go into 'fight' rather than 'flight', then where are the thousands of disabled people who get into fights all the time?
If his defence is 'my neuro pathways are shorter due to anxiety, and therefore I went into 'fight' rather than 'flight'', then I'm concerned that this sets a bad precedence for the millions of people who struggle with anxiety, stress and depression.
From my own non-medical, non-academic background, I have witnessed people under stress acting badly. Not usually to the levels of physical violence, but people who would never have yelled before suddenly shout aggressively. I suppose the question becomes what we do about that?
I suppose my argument here still stands - yes, people under stress might well go for fight rather than flight. People who have been under stress might well have this as an instinct rather than retreat or curl up. But we still don't see masses and masses of people killing other people.
I have read in reports 'I saw red and shoved him!' or 'I saw red and threw the cup at the wall and it smashed.'
What bothers me about OP in relation to this, is that these aggressive shouts or shoves or throws are generally the work of a split second. They're not 'I walked across the room to pick up a cup and throw it.' There was enough time, certainly 30 seconds, perhaps even a minute, for some of the 'retreat' instinct to break through, but a fairly large amount of what he did suggests premeditation and not instinct - walking around to get the gun, bracing himself against the wall. Even when he shouted several times.
To my mind, these don't fit well with the explanation that it was a split-second instinctive reaction born from a lifetime of stress.