They should set up 1000 sensors across the lower 48. As soon as someone transmits on guard it immediately triangulates the exact position. Correlate the data to Flight-aware and bam, you have your culprit dead to rights. {evil laugh}
I usually could care less about stuff like this, but I agree that if the purpose for 121.5 is for emergencies, then it should be preserved for only that.
You'd certainly have your butt in a sling if you did this stuff on Approach Control, or Center, and it could be determined that it was you.
I don't monitor guard, but if you're telling me it's as annoying as SeeeeeeeeeeeeeeeeeYA! Then I'm on GuppyPuppy's side