The problem with the solutions here is... they make no sense: the attack was at the baggage claim, right?
It would have been easier for the man to literally just walk into the airport with the gun already prepared and start firing. You don't get screened at the door, and the baggage claim is typically accessible from the entrance to most airports according to my experience at Detroit & Tampa anyway. Preventing transportation of weapons wouldn't have made any affect on a reasonably half-baked scheme to commit the same crime in an easier fashion, because you can walk to the baggage claim and the bathrooms from the entrance - no screening. Maybe a few guards here & there, but those will pop up anywhere once the shots start.
Guy probably could have brought a loaded and ready AK-74u under a trench-coat easier than transporting a pistol in baggage, then preparing it all in the bathroom. All that did was exploit a needlessly over-complicated loop-hole.