As well they are not likely to go through the review toward securing one. Why when they can simply like any other criminal just carry it on their person without the legal hassle and fingerprinting?
Meanwhile the 9-11 terrorists carried box cutters.
I can buy those buy the box with no permit from my local CVS, grocer, WalMart, or hardware store.
Permits slow down and keep in check good legal people, who submit themselves to such pain as opposed to just carry concealed with no permit and call it a day.