You have got to figure that he was very aware of the potential surgery when he signed with the Nats. If he went to UCLA the arm would hve been bothering him at the start of next season and at some point he would have the surgery and miss close to two seasons.He would have lost a lot of value at that point.Who better to re-hab with than the Nats.
Kevin Goldstein and Jason Parks (Baseball Prospectus) had Rick Giolito on their podcast in early August. I think it's gives the listener a pretty good idea of what went into the decision to sign with the Nats.
Rick Giolito states several times that John Savage (UCLA Head Baseball Coach) was one of his key advisers, so I'd imagine your hypothesis isn't too far from the truth.http://www.baseballprospectus.com/article.php?articleid=17891