Seems to me that the services would need 3 barracks. One for straight males, one for straight females, and one for gays.
The flaw with that argument is that the gays are sexually attracted to each other. If those who are homosexually attracted to each other are allowed to berth in the same space why can't the heteros (male and female) berth with each other?
I spent 12 years in the Navy and am a strong opponent of gays in the service. It is most definitely not conducive to good order and discipline, and neither would different hetero sexes berthing with each other be advisable.
And wouldn't that be a little bit of heaven for the gays.