Making a fool of oneself does not equate to going on a murderous rampage. I've tried to release eggplants back into the wild in the grocery store at 2 AM (don't ask....:floorlaugh

and I will admit to making a complete fool of myself on more than one occasion....
I don't think Jason was a mean drunk - he was a stupid drunk. At least in public.
I would think alcohol would make him less able to pull this off, and work in the defense's favor if he'd had a few. He was def a life of the party guy (again - if by "life of the party" you mean peeing on the floor in front of people - which apparently is WAY more common than I would have ever guessed.......)
Oh what a sheltered life I lead.....