Tueller was right.
I have to wonder why it took the officer so long to defend himself, but I can hazard a guess that is politically slanted.
If you lunge, slash and miss, I will surely draw, shoot and will not miss.
OK, maybe one or two misses of the mag dump.
I would not wait for a lunge and miss. The pursuit, with the attacker approaching into arm's length distance, is more than enough to establish reasonable fear of death or grave injury, i.e., justification for the use of deadly force. I would put my deadline around 0:27 on the video, though 0:06 is also a possibility. And I would acquit anyone who fired in self-defense at any time from 0:01 onward.