So I called an LEO friend of mine in the PR of MD who works for the other state law enforcement agency up there. This is not a legislative act at all, but a policy implemented by the MSP and carried out by their licensing division.
I would hope that someone would refuse to sign the form, get denied, then file suit.
*Side note - when you fill out the MSP Form 77R to purchase a regulated firearm in MD, you are never approved. The paperwork is returned and stamped "NOT DISAPPROVED." No, I'm not kidding.