TSA = Totally Stupid Agency, just as FBI is Famous But Incompetent. Both prove it frequently. But the rule is don't lock your cases in the US. Mrs Radeng unthinkingly locked a Delse case, and it now doesn't lock any more after TSA rummaged through.
The really disappointing thing is they take no responsibility for damaged or missing articles, which to my mind suggests that they are more than happy to have their employees thieving.