More like crackhead with a knife.

He's poor, he's stupid, he's violent, he stabs everyone who gets close, he makes terrible choices and has an insanely delusional sense of self-worth, but nobody seriously believes the police can't take him down if they really wanted to.

The concern is just preventing him from stabbing more people before they take him. And unfortunately, for some reason the cops think if they pull out their tazer, his knife will turn into a gun.