In order to make that claim, he'd have to be able to demonstrate that other people not only made contradictory claims but did it under oath. Doing it in the press doesn't count for diddly. If he did make such a claim, I assume he'd have to demonstrate where others made similar contradictions under oath - which he couldn't do since the Grand Jury testimony would presumably still be sealed. Also you're assuming that the judge would let him try to even make the argument in the first place.
However, the heart of his perjury theory was predicated upon the proposition that Mr. Libby learned of Valerie Plame's identity from other government officials and not from NBC's Tim Russert, as claimed by Mr. Libby. Indeed, Mr. Fitzgerald seemed to have a reasonable case because Mr. Russert, a respected and admired journalist, with no vested interest of his own, denied that he discussed the Mr. Wilson's matter with Mr. Libby.
However, given Mr. Woodward's account, which came to light after the Libby indictment was announced, that he met with Mr. Libby in his office -- armed with the list of questions, which explicitly referenced "yellowcake" and "Joe Wilson's wife" and may have shared this information during the interview -- it is entirely possible that Mr. Libby may have indeed heard about Mrs. Plame's employment from a reporter. Given the fact that the conversations in issue -- the one with Tim Russert and the one with Bob Woodward -- were separated by less than two weeks, and that officials like Mr. Libby juggle literally hundreds of matters on a daily basis, it is entirely plausible that he confused the two reporters. There certainly was no possible reason for him to mislead Mr. Fitzgerald on this issue, since the point he was trying to make, originally to the FBI investigators in October 2003, and later on to the grand jury, that Valerie Plame's identity was known to a reporter who imparted it to him was equally compelling, no matter what the identity of that reporter.
In light of these facts, it is at least doubtful whether a reasonable jury would find Mr. Libby guilty. Moreover, as argued by Washington lawyers David Rivkin and Lee Casey in an article appearing on today's op-ed page, under the U.S. Attorney's Manual provisions, no prosecution should be commenced unless the attorney representing the government believes that he has evidence that will probably be sufficient to obtain a conviction. Accordingly, Mr. Fitzgerald should do the right thing and promptly dismiss the indictment of Scooter Libby.
I really doubt that Fitzgerald will just drop the indictment at this point, but he will have a much harder time winning a conviction now.