If you can not obey DADT what else will you disobey. The lives of your whole unit depend on you following orders and having the discipline to carry out the orders.
Not to mention the fact that DADT doesn't really serve any benefit to the military, other than keeping gay folks out the military. Why shouldn't gay folks be in the military in the first place? Why should we keep DADT?
People depend on them obeying orders. If they can not obey DADT then they can not be trusted to follow other orders that the lives of others in their unit may depend on.
"He who does not think himself worth saving from poverty and ignorance by his own efforts, will hardly be thought worth the efforts of anybody else." -- Frederick Douglass, Self-Made Men (1872)