I thought from listening to Cooper that he felt he was released by his source in terms of speaking to the Grand Jury and the grand jury only.
It's entirely possible the source released him from all confidentiality to all interested parties (including the press), but it would serve Coopers purposes to keep the suspense out there that it was Rove (for those who don't understand that Rove has already released everyone from confidentiality).
Swamp Thing said one thing to the gj and something else to the public. Wonder if Cooper's taking a page from Sid's book.