Partly Emanuel-Axelord Clintonism; partly, a belief that national security is not as important as sustaining military homophobia as a religious value; and partly ... well you don't have to look very far to see who really doesn't want change:
“a network of gay and gay-friendly individuals and organizations worked to derail the possibility of a suspension of the ban."
Can you smell the Human Rights Campaign? It's that unique blend of cowardice, careerism and fantastic amounts of money that usually tips you off.