The Dems have done a classic Clinton on the Swift Boat guys.
By focusing on the Purple Heart issue, they've pulled the discussion away from JFKerry's anti-war activism (as you'll recall, Clinton focused on his draft dodging to pull attention away from Jennifer Flowers).
The MSM followed suite, and most Americans who haven't read the book think that the Swift guys simply attack the battle records. Of course, those of us who read the book (which obviously didn't include Chris Matthews on the absolutely last time I'll ever watch MS-NBC) know that the real damaging stuff is the anti-war activism.