Your friend's brother's conduct was the problem, not the gun.
He was stupid to threaten the transvestite with a gun he had no intention of using. If he had, they wouldn't have been wrestling for it.
I'd bet dollars to donuts, he said he was going to get his gun, too.
The purpose of a gun in this case, is to preclude hand to hand combat, keep them at bay while calling the police, if they refuse to leave.