Several years ago, I saw an excellent piece on C-SPAN about gays in the military - specifically on a submarine.
Some senators congressmen who were on committees relevant to the matter were aboard a 688 boat (it was filmed). They did a quick tour and went to the enlisted berthing are, where the racks (3 deep and several high) were shown. They then had three enlisted squids take places in the racks, one wearing a grey t-shirt to identify him as a gay sailor (for purposes of the demonstration, it was emphasized). They then took various positions in the racks, and the sailors would then climb in and out of the racks, alternating positions, etc... They would interview them during the exercise (so, how do you feel being straddled by a gay sailor in his skivvies?).
It was both ridiculous and revealing at the same time - basically that putting and keeping gays and straight in roles where they have to be in such close quarters is a definite morale issue.
It's distracting enough with women, but they've found ways to make that work with specific roles. Openly gay might work in some situations, but not in most. It's not about fairness or other politically correct BS. It's about effectiveness - they don't need the distraction.
This is the Pub. Leave common sense at the door.