Repealing DADT is unlikely to harm military readiness, according to the military's own report.
As a thought experiment, consider what would happen if every member of the federal government who has not completed at least one full term of military service recused him/herself from voting, or at least from making outrageous statements about how any change in any policy will affect military readiness. That wouldn't allow for a quorum in either the House or the Senate, and — perhaps more tellingly — would exclude the Commander in Chief, his deputy, and the Secretaries of Defense, the Army, and the Navy.
So, on behalf of veterans who care more about getting a thankless, underpaid job done — and done right — than about political posturing concerning who is doing it: If you haven't shared our foxholes, our barracks, our mess halls, and our memorial services, stop imposing your ignorant preconceptions of what "unit cohesion" and "military readiness" require upon those volunteering to put themselves in harm's way.
And while you're at it, change the Veterans' Day holiday to the first Tuesday after the first Monday in November — the day, enshrined in the Constitution, that is the real purpose of all this. There wasn't, and isn't going to be, a "war to end all wars" — so stop celebrating what was merely a cease-fire agreement in thirty years of total war as if it is more special than any other "end" of a declared conflict.