The policy is "don't ask, don't tell, don't investigate."
The only way to get kicked out is to tell.
I know a lot of people in the Navy and Marine Corps. The word I get on this topic is that the tellers are almost always lying through their teeth. One favorite strategery of the faux-rump-ranger crowd is to loudly announce that they are gay after getting Uncle Sugar to pay for some very expensive and lucrative training...and then using their veteran's preference to get a cushy civil service job with the Department of the Navy.
All the more reason to end this stupid policy allowing people to get high-priced training on Uncle Sam's dime and then play the taxpayers for a sucker.
End the policy and make them serve out their commitment.