There's some superficial plausibility to this in the abstract: Wolfson: Edwards' Cover-up Cost Clinton the Nomination. (The idea is that if Edwards had been pushed out pre-Iowa, then Clinton would've won Iowa and Obama would never have caught fire.) However, it reads as the nuttiest of media-bias-killed-Clinton stories. No wonder they didn't expose the Edwards affair -- it would've hurt Obama!
And I don't really buy the claim that Edwards was stealing the Clinton vote in Iowa. The exit poll data do not show Edwards running strongly with seniors or women or lower-income voters; in fact Clinton was winning her support base outright. The Edwards contingent -- actually, a lot of the Edwards vote was redirected from candidates that failed the 15% viability threshold -- is disproportionately upper-income, middle-aged white guys. These voters went heavily for Obama in Wisconsin.