It doesn't just cover service members, they would classify as appointed officials.

"a bill to protect United States military personnel and other elected and appointed officials of the United States government"

Edit: Jeez, just read it, it's not even long. They would absolutely fall under it.

The act gives the president power to use "all means necessary and appropriate to bring about the release of any U.S. or allied personnel being detained or imprisoned by, on behalf of, or at the request of the International Criminal Court".