I don't know what the NBA rule specifically is on this, but if this happened in a HS or college game and the official saw it, the player would almost certainly NOT be ejected. The intent of the rule is to keep them out of the goings-on, not keep them from initially acting on their instincts or creating an electric fence. Plus, the coaches were right on top of it.
What if the altercation went into the bench area and the players on the bench had to retreat to the court to avoid it? Would you suspend him and others then?
Again, I don't know what the NBA rule says on this and I'm sure teams get league advisories on what to do in these situation. The way to end this sort of nonsense is to start kicking players out of series (or serious suspensions during the season), but that's never going to happen. The NBA is 100% PR and nothing more.