First of all, Novak is not an idiot and he did not "blow her cover".
The only cover he blew was Wilson trying to claim some kind of higher ground in his representation of his trip to Niger and the scope of what he claims to have learned and who was privy to these "findings" (barely anybody).
Novak did a public service by providing this angle, that Wilson was sent because his wife worked at the CIA.
Novak was not smart enough to figure out how this would play out. Even an idiot could have forseen it.