The first is that if indeed this offer was made by one or more members of the Obama administration, it was corruption, a felony. The second is that it was Joe Sestak's legal obligation as an American, and more importantly his duty as a retired Admiral, to report it to the authorities as soon as it happened.
The third observation -- and most important -- is that Joe Sestak did no such thing.
Sestak is making a big deal about his integrity in answering questions about the offer honestly. If he truly believes that, he can't hide behind the, it's up to the other side to comment, defense. Sestak is alleging someone in the Obama administration committed a felony. He needs to come clean.