1.the Chinese extended their review 2.rumors that google wants out. 3. fear that the Chinese will demand such onerous conditions google will want out.
the only one of those that is fact is the Chinese extended their review, the rest are just speculation. having said that the spread is pretty wide for a deal that is close to closing. So imho its either pricing in a very long review process or fear of 2,3 listed above is keeping the spread wide.
I have no strong opinion one way or the other, I was not expecting the China thing in the first place.