Theory; the DNC is using this to fundraise. In bringing a dead issue from the grave by attacking FR with a worthless C and D, the loony bin will be opening their wallets in praise of Dean’s attempt to stifle free speech... Simply a fund-raising awareness event at the expense of move-on and the governor. That is why they released this “confidential” letter to others.
You may be right, but if that was the intent, it hasn't worked that well at DU. When I looked at their thread a few hours ago it hadn't been updated for a couple hours and the enthusiasm was, well, tepid. Some loved it, some were unsure whether the threat was enforceable, and others were concerned about how such a demand could affect their rights. Not the kind of response one would want from a fired-up base.