Sure, it was not a functional weapon, but she looks smart - kinda like MacGyver. And he could turn it into a functional device to take over the plane and force the stewards to act straight, or at least less queer, and the stewardess to give out more drinks and peanuts like in the old days. She looks like the type who could take over the cockpit with just a sheet of paper, (don't laugh we all know how painful a paper-cut can be.) Just the image of a gun is enough to make some liberal wet themselves, and who knows if this girl was really a girl and not a terrorist covered in an elaborate full body suit and the gun on her purse a part for a more nefarious device to trigger an EMP pulse high in the atmosphere so that kids could no longer get their iTunes and disable the IRS datat center - the key to the device being cleverly camouflaged as a gun to throw off federal agents, who would of course ignore the purse because it is not a "real" gun. . I bet you didn't think about that did you!
Or it could be that the TSA is dumb as rocks, (no offense to rocks intended).