Honestly, all of the shit making fun of retards isnt right at all. It is not the individual's fault unless it was drug induced, in which case oh well, screw 'em. But yeah, lay off the mentally ill a bit.
Whether or not he was mentally handicapped isn't the argument here.
Was it right or wrong? The only relevance to his being handicapped is his instability, which the officers would have assumed anyways when he was running around butt *** ***** screaming "you'll never get me" and all of the other crap.
Cops did the right thing. They protected themselves and the dude's mother who was also probably in harms way.