True, but those people are already going to vote for him. The undecided, for the most part don't like being manipulated with lies, and this is just the kind of thing that turns a lot of voters off. Furthermore, if his campaign starts to look like it is in panic mode with wild accusations a lot of Kerry voters will stay home. What is helping Bush is how comitted his support is to voting.
You know, I as much as anyone can't stand all their lying bullsh!t. But I think your analysis puts it in the exact, right perspective. I'm sure Karl Rove is considering this too, as he has to decide when replying is a good or a bad move.