The only part of his story that may not add up is the number of shots fired as far as I can tell... and people are notorious for getting that sort of thing wrong.
He didn't call the cops because he though the guy got away clean... very possible.
Refused to answer dispatcher's questions... that's what most people will tell you, don't talk to the cops without a lawyer. I bet you that's what his lawyer told him to say.
Maybe there is something going on that the story isn't saying, but I'm not seeing evidence that he did anything wrong.