I think this is an insult...
Not necessarily, it might be referring to the disharmony theory rather than the "gays can't fight" theory.
I am mainly making a stab at weak humor, but this second theory is more what I think. "Gays can't fight" doesn't make sense, since they are already in the army, fighting. Open homosexuality makes things weird for some heterosexuals, even though they are the same guys working together. Kind of like, you might find a new dish your wife cooked really, really tasty until you find out it's horsemeat.
A question I find interesting is, what's the point of separating soldiers' showering facilities into "male" and "female" anymore (assuming they still do that kind of thing)?
Having queers in the military will be a positive thing for the military. It will increase effectiveness of the modern integrated army. Many societal advantages to having open homosexuals in the military. It will help keep the female soldiers in check. Attractive females who are good at using favoritism from superiors to get by, cause a lot of internal infighting. Jealousy issues will be moderated by the presence of gays, who have a tendency to be fairly level headed about this sort of thing. Also many ex soldiers who would have been lifetime Republicans will support Democrates. This is a admirable statist move. Bad news for us liberty people though.
What is wrong with horsemeat?
It is difficult to properly masterbate in a public shower if the opposite sex might walk in. Another guy just points and laughs, I don't even like it when my own wife catches me jacking (and she saw my dick before, a year or so ago). If a chick tries to rub one out and a guy walks in, he will always suggest a "alternative", and if he has a small unattractive dick, it is awkward for the chick to tell him "no". That's the reason for separate facilities.