Bold of you to assume that the airline personnel are familiar with the actual TSA regulations or have been trained to follow them.

The same rule existed to allow checked musical instruments but it was so common for musicians to be refused the ability to check their instruments in the coat closet that Congress literally had to get involved and pass a law that allowed checked instruments, and yet, almost 20 years after that law was passed, I still have to argue with an airline employee like every other time I try to travel with a guitar.

In my experience the people running security are morons who are barely familiar with the rules they are supposed to be enforcing.