I think you're missing the point. A mere week ago, it was Amos who sounded as if he would lead the charge to fight implementation of homosexualism in the military.
But now he's surrendered.
It is Amos who has run up the white flag.
Amos never said a word about fighting implementation of the repeal. He was fighting the decision to repeal. There is a tremendous difference between those two things.
Seriously, this shouldn't be a difficult issue for people to understand. It is the responsibility of an officer when asked his opinion to argue strongly and openly in favor of his position. Amos did that. But once the decision has been made by lawful authority, and the order issued, it becomes your responsibility to carry out that order to the best of your ability even if you disagree with it. Presumably, Amos demands that of his subordinate officers every day, and he would be setting a horrible example of that if he did otherwise.
I would have been just as understanding if he'd chosen to resign, but I don't think that was compelled as the only honorable course. Frankly, I think he might have felt he was abandoning his Marines when they needed him most, and that's why he decided to stay on.