No one has to "serve openly" in the military. Everyone with half a brain knows who the homosexual service members are. Don't Ask, Don't Tell only served as a good "get out of the military free" card. The guy/gal would be underway/deployed and start missing home/boyfriend/girlfriend, or feel he/she was treated unfairly for whatever reason and just come out of the closet to his/her superiors. He/she caught the next plane back to the states to work in some office while waiting to be processed out with an honorable discharge.
"HOW CAN YOU SAY THAT?!?"
I saw it happen on more than one occasion. That's how. In fact, a Navy friend was on his first deployment and started missing his boyfriend back in New London, CT. He came out of the closet while underway. His boat pulled in somewhere in Italy and he was on the next flight back. Unknown to him, his boyfriend decided to join the Navy during this time and was off to Great Lakes, IL for boot camp before SAILOR 1 "came out." Sailor 1's plan didn't work too well.
The fact is this; no one cares if the guy is gay or not. If he does his job well and doesn't make any unwanted advances, good on him. Sexuality should never come into play. "Serve openly" is a joke. How about you serve your country openly as an American and forget the rest of the garbage?