Why this leaves you smiling I don't know. Police obviously want to reduce the number of guns that citizens have; this makes police more necessary. One of the overriding goals of the State is to maintain a monopoly on the use of violence, so that the resistance to their initiatives is limited.
If I disagree with, for instance, the income tax, I could choose not to pay it. Soon the police will come, and attempt to use the threat of violence to compel me to accept whatever punishment the State deems fit. Obviously the police would prefer if I was unarmed; if I had a weapon designed to punch through bullet-proof vests and kevlar helmets, the police would have to question the necessity of using violence to enforce the will of the State against me.
How many police officers are willing to risk their lives to ensure that the gore-encrusted cogs of the State machine keep turning?