There's also another article from Toensing arguing why Plame wasn't covert that I'll post a link to tomorrow if I can find it. I can post many more links to credible arguments as well. Your claim that there isn't a credible argument against her covert status is just silly.
Here's a reference to Toensing in a column Novak did about her covert status:
That decision left the field last Friday to such partisan Democrats as Rep. Chris Van Hollen, chairman of the Democratic Congressional Campaign Committee. Rep. Diane Watson, Waxman's fellow Californian, mimicked the chairman's inquisitorial style. She repeatedly interrupted lawyer Victoria Toensing, the lone rebuttal witness granted the Republicans by Waxman.
Toensing testified that Plame was not a covert operative as defined by the Intelligence Identities Protection Act (which she had helped draft as a Senate staffer in 1982) if only because she was not stationed overseas for the CIA the past five years. Waxman hectored Toensing, menacingly warning that her sworn testimony would be scrutinized for misstatements.
Was Valerie Covert?