You think they shoot rifles off that thing? Not even a little bit.
He’s not in a role that would ever wield a rifle in a realistic scenario. It’s not part of the Navys standard training for sailors or officers either. If you ever have to fire a gun in the Navy, you’re already deeply fucked. You tend to shoot things with lot more range off a ship, and most aren’t something you can sling over your shoulder.
It’s no different than a marine commander standing at the helm backwards or a high ranking army officer having a life jacket on backwards. Its a simple error borne from inexperience, not incompetence.