This is classic "what not to do in a SD situation"...
What the vic should've done is this:
1. Never take your eyes off the aggressor(s)
2. Be aware of your surroundings
3. Look for an escape route and try to position yourself near it
4. Put down the goddamn phone!!!!
5. Raised both his hands and attempt to diffuse the situation - helps block potential face strikes too.
6. As soon as intent is clear and combative distancing is breached, duck and taken the knee of the lead leg out first
7. NEVER EVER TURN YOUR BACK ON THE AGGRESSOR. NEVER....
8. Never get into a grappling match with someone that size. Always take out the joints first - preferably the suspension ones FIRST.
9. Always have a follow-up technique or 2 or 3 or 6
10. Be prepared for spectator involvement and if necessary, remove the threat
I don't know that I would do anything differently, or that any MA training would have helped. It's easy to be an armchair commentator. In reality, many in that situation would not be able to overcome the adrenal dump and would've been frozen to the spot. The only way I've found to avoid the adrenal dump is to suspend all ethical and moral consequences and go for the quick "kill".
Not very "aiki" (whatever that means) - but when one's life and livelihood is at stake, I don't know that any other response would be appropriate. Especially, not when said aggressors are intent on assaulting and occassioning bodily harm to you.