I have a hard time believing that, it's similar to a President making a deal with a potential appointment - I don't think either is appropriate and hope justices are above deal making - but that's just me.
It’s just a rumor, what is known that Kennedy wanted to retire and he did. Maybe that list with several of his clerks on it may him feel it was safe to retire. That is far more likely then the deal rumor. I probably should not have brought it up.