He could fire - if he put the safety off. The guy knew how to use a rifle. The fact the safety was off shows he had no INTENT to fire. The cops were, in fact, in no danger. Who gives a cr@p what the cops "thought". They were the most dangerous thing around that day.
They claim he pointed the rifle at them. I was under the impression that people who know how to use firearms don't point them at people they don't intend to shoot. Either this Marine didn't know how to use a firearm, or somebody is lying.