Like I say, I would have been happy for the situation to have been dealt with using non-lethal weapons.
Nonetheless, I think it is quite a thing to assume that situation could have been so easily handled- that thing is always easy to say in theory commenting afterwards. I don't like cops using guns, but I would definitely say that guy was in a situation where pulling the gun was reasonable in the heat of the moment, especially in the professional way he used it. He was not out of control- he made a reasonable judgement about how the situation needed to be handled.
In so far as American cops carry guns by default, that's a political issue, and a different debate- in that respect, I do believe that if American cops were not routinely armed then a person like this would not have needed to die. But as US cops are armed by default, the thing that causes controversy is the poor gun discipline they often show, as I outlined above (and which I think is more or less inevitable when you arm an entire police force, as good gun discipline in law enforcement is frankly difficult and you can't expect all cops to have the right temperament for it).
By those rules, this cop was fine. He didn't provoke, he didn't abuse, he didn't go wild. You may not agree with his choice but he was within the rules.