There are a number of things that can happen in a case like this and so he needs an attorney to help him. I live here in Moses Lake and have worked here for 21 years. I can help. Call me or email me and we can meet. I handle these type of cases all the time.
He should get an attorney. After looking at all of the evidence and interviewing the witnesses it may make sense to assert self-defense and elect for a jury trial. Assault cases are easily filed, but relatively hard to prove beyond a reasonable doubt.
Scott W Lawrence
(425) 488-8481 Office
(425) 971-7347 Text
Security guards, especially concert security guards, always screw this stuff up. They are transient like carnival workers. I would be shocked if they can put together a good report and / or show up for a trial if the matter has to proceed that far. You should hire him a good attorney familiar with concerts (and the fallout) in that area. Best of luck. My suspicion is that he will be OK.