Kalitos The way Treyarch did the perk script assumes every perk is available on every map because they wanted a global script to handle multiple different perks. Just because code relating to or referencing is in _zm_perks.gsc doesn't mean the perk will work in every map.
The default perk code will crash if you try to give a perk not on a map to a player because it can't find the perk bottle weapon. Also the clientfield won't work either so it won't show up in the UI, but the perk icon wouldn't be available anyway.