"We" don't argue she was not covert. It is relevant to the law at issue as to when that aspect of her employment ended.
As to Rove's role, he's but one in a cast of characters despite the current renewed focus on him. Of course he had nothing to do with outing a covert agent. That was obvious back in the beginning of this nonsense.
The secrecy doesn't end just because you're no longer covert, though. Why go down that road? Rove did not say she was covert. That's the end of it, unless and until they can prove that someone else outted her.
Let me tell you where this is really leading, and where the prosecutor is headed. He's hoping that he can catch someone in a lie. He doesn't give a damn whether she was illegally outted or not. It's a crime to lie under oath to a grand jury, and even if Rove did not out Plame, he can be prosecuted if he told a lie to the grand jury.
Of course, that has nothing to do with the hubbub in the media. They have no idea what Rove told the grand jury.