The jiu-jitsu master was not alone. What street fight against a twig of a man? Punch the dude a couple of times, drag him out at the next station, hand him over to cops.
It is sad that someone died, even more sad that it was a mentally ill person that should have had help 32 arrests ago. The less lethal argument always irks me though. This could have went the other way in a second, you could have been stabbed in a major artery and bled out in 20 seconds. Stating that he was not alone is irrelevant, the chance of a stranger stepping in to help you in a street fight is almost zero. Most people go straight into flight/survive. Most people will step over you as you're bleeding to death, and later take photos of your corpse and talk about how wild their day was.
I would like to state two simple truths
1. None of us were there, our lives were not in danger. Arguing over the potential for less lethal from the safety of our smart-device is kind of moot.
2. Being mentally ill doesn't make you someone else's responsibility.
The jiu-jitsu master is not a social worker, he does not work for the state rehabilitating mentally ill patients. He's just some dude that knows self-defense. It's sad that it happened this way, but I don't know how anyone expects the common man to do anything about it while our literal state and federal governments haven't lifted a finger to help, ever. Mentally ill people eventually get so sick they are classified as "bad", outcasts to society, and those people end up in prison. Every single violent offender in prison is or was mentally ill in some way, it's just easy for us to classify them as "bad" because they are so far gone we mostly regard them as irredeemable.