You forgot the "who didn’t even pay his fare"... which makes a big difference.

In this particular situation it doesn't appear to, but in many states you only have the right to 'stand your ground' in places you are legally allowed to be, so if you don't pay your fare you eliminate any sort of "stand your ground" defense as to why you stabbed someone you thought was threatening your life rather than ran away.

So this might kill his attorney's opportunity to even claim that the Ukrainian woman was tormenting and threatening his life or something. It's one of those things that sounds irrelevant but turns out to have a gigantic impact on self-defense claims, which really, are the only hope the neck stabber has of not going down for some kind of murder charge.