A persistent, enthusiastic Nader voter is much madder (more hate-filled) and radical than any three likely "I don't like Bush" Kerry voter.
I wouldn't recommend pissing the Nader voters off.
Kerry so foolish a campaigner that he might anyway, but if Kerry is a "likely" loser against Bush, then the Nader voters will definitely want to cast their protest ballots to the person they prefer. Nader.
You know, I can at least respect the solidly Nader supporters because they rufuse to let this a campaign of just hating Bush.