He tried to tell the officer he was carrying concealed but was cut off. He can now sue the officer for abusing his authority under color of law and making an illegal arrest.
That is the only real way to make sure this sort of thing doesn’t continue. If the police know they are going to be in deep s*** and lose a ton of money, then they will do something about it. Heard it worked real well in Arizona (I THINK, possabley another south western state) when the police arrested a guy for open carrying. State law says that locals can’t make more restrictive laws so now they are minding their manners.