This is not unique. There was a video going around of a teen(?) in a subway station resisting cops, and one of them drew on him and fired. Thought he drew his tazer.
Procedures are supposed to include one cop with their firearm drawn and the other with the taxer, just in case the tazer doesn't work.
Goes to show one more time how cops are trained to use their weapons rather than attempt to subdue by manual force. I blame it on the recruiting policies that allow relatively physically weak candidates to become cops. In the field, they have to rely on their weapons more than their hands. Their perceived weakness may also increase the number of times they encounter an attacker simply because the attacker views themselves as more capable against a weaker cop. Escalation becomes inevitable. Were the attacker less confident, compliance would be more likely.