Personally, I don't see much redeeming value for a gun that is designed specifically to penetrate a bulletproof vest. You might make the argument that criminals use bulletproof vests, but it seems far less likely that this gun would be used to defend against a criminal with a bulletproof vest than to shoot a cop with a bulletproof vest. Of course, I'm not an expert on that, but I'm willing to leave that decision to the legislature.
Criminals CAN get bullet proof vests. ANything can be bought on the black market.