He almost certainly had a weapon, but he didn't do anything any objective observer would classify as threatening. He toked up in his car then freaked out when a bunch of cops started pointing guns at him and screaming. That's not something you deserve to die for, and these cops should absolutely be held accountable. That police train themselves to use force recklessly does not mean the policy is actually right, morally.
The problem is, the police have no way of knowing
why he held on to his weapon (assuming one was there). As long as he keeps it, he can use it and being high and scared, doesn't make him less of a threat.
The problem with this situation (again, assuming a gun, because I can't tell), is that it's a complete gamble: If the police wait and he raises the gun, he'll be able to get a shot off before they can stop him and possibly hurt or kill an officer or nearby civilian. Maybe he won't do anything or maybe he'll kill someone. Those are the risks. I don't know if it's fair to say: "Well, wait and see if he tries to kill someone first."
Just having a weapon isn’t enough. The person has to show intent on using it and from these videos he wasn’t showing any intent at all. He was walking backwards with his hands at his side. If he suddenly made for a quick action like he was reaching for the weapon then yes that could be justify. However, from the looks of the videos it’s not. Also they already had their guns drawn on him, if he would have went for his weapon he would be dead before he could get off any aimed shots.
I think he's showing intent to use the weapon, by not dropping it. I mean, again, maybe he wasn't going to do anything. But as long as you keep a weapon, it's possible you're planning to use it. Also, I'm just relying on what I heard on the news: I heard an expert state that tests have indicated officers
can't react fast enough to disable someone, if they wait for them to raise the weapon? But who knows, that could be wrong?