Tough call for any officer to determine if or not an individual is drugged or has mental conditions when a lot of drug addicts have mental conditions in the first place. Both of which often have unusual strength.
If or not the guy was a menace or not really isn't relevant, since he was argumentative and resisting from the start, then tried to run and also apparently got his arm loose and went for the officers gun.
Recalling also the fellow who called in saying this guy was acting and talking weird....adds to the defense of the officers as well for they also saw and heard this.
Your father was wise saying
“never attempt to flee or fight the police”.....this fellow would still be alive had he been instructed so perhaps.
He was an adult man in his early 20's. We don't know for sure whether he was on the "spectrum"; we're just guessing here. But, obviously, he was capable of doing things on his own, like walking to the store to buy something.
Argumentative and resisting?? Resisting what exactly? Why were the police even bothering with him? Who cares if someone wears a ski mask and behaves oddly? There are no laws against that