<-- Texas here. I've been in more fights than I should have been, and never got charged, though I did get detained one time until security camera footage was reviewed in a situation where I beat the holy crap out of someone who kicked their small child in a wal mart.
In this case I totally understand why the guy punched him, and why he even wanted to go punch him twice or kick him : he really could have been a threat. When someone is drunk and aggressive, you really don't know what their intentions might really be. Who knows if he's carrying a weapon or going to pull a knife (or grab one from the table) and stab you. Once someone is in close proximity to you and your loved ones and starts acting in a really threatening manner, I think it's legit to KTFO their dumb ass if they are dumb enough to use racial slurs against you.
I don't think this would have been a case here in Texas. In NY, I understand the namby-pamby gov't nanny wanting to make everything in the world illegal, but I can't imagine a jury convicting him of anything. Particularly when one can't say with any seriousness that it was his intention to knock him to the ground and have him seriously injured (that just happened to be a happy accident!).