Actually, I think what Dole was doing (when he gave advice to Kerry a while back) was shrewdly laying the groundwork for what he (Dole) is saying now. I'll bet you Dole has long resented Kerry's slander of other Vietnam Vets, and knew that his (Dole's) advice to Kerry would fall on deaf ears...but would lend credibility to Dole's criticism later on. Way to go, Dole! It's going to be very tough for the Dems to dismiss Dole.
I think that after Dole saw the new swiftvet's ad he felt motivated to speak out. The best part is it came as a complete surprise to almost everybody. He gave it to kerry with both barrels blazing. Couldn't have come at a better time for the swifties with the new ad starting tomorrow.