Your assertion that being arrested is somehow a violation of anyone's rights is absurd.
Especially when the person being arrested has just discharged a firearm in public.
(Police harassment is a thing, but not as pertains to this story.)
Being arrested doesn't mean you're guilty of anything. It means a police officer has probable cause to think that a criminal investigation is warranted.
It is up to a judge and/or jury to decide if a law was broken, not the police.