Flight Diverted By "Threat" From U.S. Air Force Intelligence Specialist

I think I get it. He may have learned something he wasn't supposed to know, and was afraid some agents may be waiting for him at the end of his flight to kill him. So, by declaring he had a bomb he was put into the immediate custody, and thereby safety, of federal law enforcement. When his superiors come to talk to him, he'll tell them what he knows.

Pretty quick and daring thinking.