Here's why TSA locks are supposed to be illegal for Rifle cases, gentlemen.
The locks on guns are deemed non-tamperable. Therefore, if under your direct supervision a foreign power's customs opens your rifle case and they find machine guns, or 50lbs of coke, or a six year old boy, you are prima facie guilty of whatever crimes apply. You are purposefully denied the defense "its not mine, I didn't put that in there, I'm innocent I tell ya!". TSA / Customs is not supposed to open your gun case away from your view for this very same reason, whatever is in that case is YOUR liability, you can't say somebody put it in there while you weren't looking.
That's why rifles are supposed to be locked with a device only you, the authorized owner, can open.
TSA locks are a joke. First of all, you can brute force hack the lock by trying all the combinations. Second, TSA locks have roughly 20 "top secret" keys that only the TSA is supposed to have. But of course, TSA being morons, their clerks took photos over the years that featured their keys so the dark web has 3D print designs for all the TSA numbered keys. TSA locks are A.) Junk, B.) Easily broken, C.) Easily guessed combinations, D.) Keyed to a key that anyone can get, and E.) Can be picked in 10 seconds by an amateur.
TSA Locks are designed where the TSA needs to inspect. This applies to luggage and ammunition. It is the opposite intention and purpose of a gun case lock from a legal perspective.
Asking the TSA this question is ill advised as they are morons at every turn and if they give you an answer, it isn't a defense in court anyway. "TSA clerk told me" cannot override the various statutes.
@wesheltonj is my jurisprudence sound on this matter?