This is odd at many levels.
Military in uniform and on orders aren't supposed to be searched. Period.
Then I've had a bag that popped positive on the swab tests due to exposure to the elements in Iraq. All they did was re check it, call a supervisor and perform a hand search. Then I was free to fly. No problems since then domestically or internationally.
So why would a Marine get pulled out and detained? Something isn't right with this story.
Yeah, he failed a swap test from a prior trip. He gets on a TSA list, which at this point, has no petition list to get off of unless you are the Cape Cod Orca with initials T Kennedy.
I have no idea if he was in uniform, or anything more specific than the information presented in the original article.
It's mostly likely that the TSA list is Hotel California. You can enter, but you can never leave. That is...unless you get drunk and drown your evening lay.