I've reread the article and cannot find where it says he was a 1st,Sgt. It says "Senior Master Sergeant Phillip Monk". Senior Master Sergeant, is an Air Force rank.
Sorry - I’ve read several versions of the story. This one didn’t mention that he was a First Sergeant. Here is one that does:
http://radio.foxnews.com/toddstarnes/top-stories/airmen-punished-for-objecting-to-gay-marriage.html