There is no reason for the "but" to be in that sentence other than to create a psychological inference that despite the subject having a gun, the cops did something wrong.
Exactly....if you avoid arrest while armed you could be a threat period. The coppers don’t have to wait to return fire, you need to take out the threat.
Here is a thought for our lower caste citizenry: Don’t do a crime and you might find out your chance of being killed by the police is about the same as anyone else not doing a crime.