You've got to consider the likelihood of that risk though. From a 50 year old Asian I wouldn't expect you've got too much to worry about.
What does his ethnicity have to do with it? Other than the increased possibility that he has done some form of martial art 😉
You are right, you do have to consider the likelihood of the risk but you have no idea what the pedestrian is saying, you have no idea what part of new york that is (chinatown maybe?). The asian mans body language is pretty confident, and pretty threatening. He doesn't look too old or frail to me, and size wise he is well matched to the cyclist so again I would say why take the risk – even a small risk of being shot, stabbed or assaulted is more than I personally would like to take.
Although it might seem like a gross overreaction to some people on here I think the cyclist handled that well. He didnt lash out initially, he tried to leave the scene, the asian man continually followed him with aggressive and confident body language.
When the cyclist did decide to take action he made it definitive – he didnt just hit him once and aggravate him – he showed him who was boss and put the aggression right out of the guy. As my old Sifu used to say – better to be judged by twelve than carried by six.
I wouldnt use a lock as a weapon like that, but other than that I don't think there is much else to talk about there without knowing much more about the incident.