I'm limited in how much I can comment about this without knowing PD/SD OOC protocol, but for DOC I don't allow people to just magic anything from a vehicle with /fl. They need to RP putting specific weapons, clothes etc inside vehicles if they're to be used from the vehicle. There's a chance they already limit this in PD/SD so there's not a full Armory in the vehicle but I expect they're held to the OOC standards already of not being able to pull things out of thin air with /fl.
Specifically only taking 1 from the station however, that's an IC restriction if that was ever to be thought about. But from the vehicles themselves, they're already expected to RPly have the weapon in there moved from the armoury.