In this case one man was carrying an illegally displayed weapon (It would have been legal if it had remained concealed and he possessed a valid concealed carry permit, I am not actually sure that a billy club is illegal in PA anyway.). That man was arrested and removed.
The other man, a resident of the building where the polling station was located, was determined by the responding officers to be doing nothing illegal and no action was taken.
There was nothing at all illegal about the "uniforms" they were wearing. If you want to appear at the polling station in a cheerleader outfit or a Gestapo uniform, your right to do so is protected. You may even wear buttons and other political statements on your clothes when you enter the premises to vote if you so choose based on a court case this year.
You may not verbally threaten someone and you may not display a weapon openly. The individual in question was arrested for violating those laws.
Are you suggesting that they should have been arrested because they were black?