Of course Obama will never actually show up, but at least they're keeping this story in the news:
The subpoena seeks to compel the testimony of President Barack Obama who has, on several occasions as President and Commander in Chief (and previously as a Senator and Presidential Candidate) called on the LGBT community to "pressure" him to change the DADT law and policy, thus allowing gay service members to serve their country openly and honorably.
The subpoena of the President is necessary for the defense to prove that Defendants were following and obeying lawful orders or directives by their President and Commander in Chief, and were therefore under an obligation and authority to act as they did in order to pressure him - in a non-violent, visible way - on this important public issue. In addition, these statements support the contention that Defendants were acting out of necessity, in order to prevent discrimination and greater harm to gay service members now serving.
I predict, as a lay person, that that defense won't actually work. But I have to respect the creativity of the argument, and how it puts the focus back on Obama's campaign promises.
DADT repeal has already been hung around the Democrats' and Obama's neck by the right. No one who would vote against someone because of that issue would vote for Obama anyway at this point. Why not try to make one constituency happy and get it done?