Is the only objection here to the fact that sodomy is included in the charges? I can see that objection, but the issue here appears to be that the two lesser grade airmen raped the staff sargeant. I know that it's arguable whether the sargeant was consenting or not, but if she was not consenting, then what the other two did was the same as date rape and I think we can all agree that date rape is unacceptable.
As to the commander-in-chief being able to romp around the oval office, white house swimming pool and heaven knows where else, while the lower ranks get hammered, that's life. When these people sign up for military duty, they know the rules. If they don't, then they haven't paid much attention to the news. They voluntarily agreed to be subject to the code of military justice, which, by the way applies to the Chairman of the Joint Chiefs of staff down to first second boot.
The President, on the other hand, is not subject to the Uniform Code of Military Justice. He/She does not agree to that when elected. Hell, if our presidents (Clinton, Bush, all of them) were unable to engage in some form of adultery, they would never make it to president ;-).
All of that said, if all of this had been three people having consensual sex, I agree - put our resources where they are needed, not tracking down people in their bedrooms.