May be a while before we get the whole story, but my guess is that he 1) was confident that he could win the starting job and 2) felt like he was on the three year plan, three years starting at UGA and then on to Sunday play. When he didn't win the job and started looking at a minimum of 1 more year as a back up, he realized his timetable was not going to be realized in Athens, so is looking for an alternate route still wanting to get to the NFL as quickly as possible.
Whatever the case, best of luck to him. I'm sure some HS Senior QBs are taking another look at Georgia.