My guess would be that now that the Democrats and their leakers have seen the actual memo and have been briefed by Williams, they realize there is nothing there; hence, this tactic.
That doesn't make sense. Why would the Democrats want to discredit this guy if they knew his report really had no meat to it?
If anything, they'd want to pump this guy up to make him look like he was worth more then he actually was.
I'm afraid if anyone's trying to discredit Williamsn, it isn't the Democrats. And think about that one, guys, and what it implies...