If you watched the press conference you would know he went out of his way not to do that. He refused to even speculate about her status in response to several questions because he wasnt charging Libby with anything related to that.
I did watch the press conference, and I agree that he was careful to not assert "covert status" asa ammter of fact. But he did say that Plame's status within the CIA was classified, etc. (using similar language as what appers in the indictment), which IMO, will raise in the mind of the casual listener an inference that Plame was covert.
He went on in the press conference to express -generally- how important protection of intelligence is to national security. That rhetoric would tend to reinforce, agin to the casual listener, that an illegal leak occurred - even though he takes pains later on to say that the allegation of an illegal leak is not in the four corners of this indictment.