When Clinton altered military policies concerning sexual preferences he opened up a can of worms. When soldiers go into the "field" they are provided 1 shelter half. Two soldiers join the "halves" together to make a tent. That tent is shared for sleeping . I think that certain Troops might takes exception to such sleeping conditions. Amplify that sentiment in a barracks or a ship or in other situations requiring close living quarters.
The bottom line is that it could be bad for morale. That could effect individual performance. The Military could lose a battle because of disgruntled Troops compelled to endorse a lifestyle which personally offends them. Losing a battle could result in losing a war. Losing a war might interfere with our freedoms!
Simplistic for sure, but there are reasons that the military has policies, and society has mores.
When clintoon won the first time I walked into a saloon and one of the guys I know asked me my opinion about "gays" in the military. I said great (which just about floored him) and then said ya never have to dig a "grenade sump" in your fighting hole again.
If a grenade comes in you just throw the fag on it.