But, as the linked blog post (by Jane Hamsher) indicates, he doesn't have the votes in the Senate and he hasn't put the weight of the presidency behind getting Senators to vote for repeal. He seems like he's using the statute as an excuse, so that he can play both sides on this issue. I understand the political motivation for that, but it amounts to breaking his promise to end DADT.
That's just an excerpt. There's a lot more that Prof. Althouse criticizes effectively.
At one point, President Obama had 60 votes in the Senate and a majority of the House. He could have tried to push through statutory repeal of DADT then. That he chose instead to push TARP, health care reform, and financial regulatory reform was neither unreasonable nor irrational. But it does suggest a certain hierarchy of issues, and gay rights was not at the top of that hierarchy.