It is a disturbing story.
Would be interesting to hear, as Paul Harvey would say.... the rest of the story.
In my line of work, I am around many, many people who drink and/or smoke weed.(believe it or not, people like to get high at concerts...
)
I have never seen anyone under the influence of marijuana only become violent. I have seen dozens and dozens of people drinking become violent.
Ask any cop or event security and they will tell you the same.
Granted, this is anecdotal evidence, YMMV... But I think dude had other issues, besides a pot cookie...