In more proof that you are wrong, you can be charged for thinking you are a cop, and as a citizen you better not make a single mistake.
Man shopping for coffee creamer at Walmart attacked by vigilante for carrying gun he was legally permitted to have
After yet another mass shooting, a concerned citizen saw a man carrying a gun. The man was legally carrying. If a cop had jumped him, the cop would have gotten off with the department saying the officer was doing his duty. If a cop had drawn and fired, same result. The argument would be the cop had no way to know the man was innocent. The citizen was arrested for felony battery. He was convicted by a jury.
Florida Man Found Guilty of Battery For Attacking Concealed Carrier - Bearing Arms - Concealed Carry, Florida
You do not have the authority of a cop. A citizen can not enforce non existent laws because they thought they were right. A citizen can not attack someone because they thought it was OK for a cop to do it. I would say if you wanted to do that sort of thing, join the cops, but they have too many jackassed morons who do that sort of thing already. One more certainty won’t help their image or reputation.
Your argument that the cops have the authority so you as a citizen have it is asinine. You can’t put emergency lights on your car because the cops can. You can’t pull over a car because you think the driver is drunk. You do not have the authority of a cop.
Foster thought he was a hero. He believed he was trying to save lives. He went to jail. He was convicted. He was sentenced to among other things probation and anger management. He lost the right to own firearms himself.
He did not prevent a mass shooting. He did not save lives. He wasn’t a hero. He was found to be what he had been all his life. An enormous ass.