Maybe, but then he could have just come out and said “I misinterpreted what I thought was an offer but which really wasn’t.”
Instead, he doubled down.
Legally, that would work but politically it's a disaster for him.
He's trying to not look like a lying weasel, but eventually that's going to be the course he has to turn to. He will not throw Obama under the bus, if only because he'll be persona non grata within in his own party and will have no hope of getting elected without their support.
Legally, nothing will come out of this whole episode, but it's a great political hammer against Sestak, Obama and the Dem Party in general.
Maybe the Administration’s goal is to make Sestak be perceived as unstable and untrustworthy, forcing them to ask him to step aside for the good of the party, and turn to Arlen in his place to save the seat. Maybe the whole thing was a set-up just in case Arlen lost?