Probably wanted a 1st retainer jockey job again instead of feeding on the Appleby/Suroor scraps that Buick discards – being second to Godolphin, I doubt that he viewed being second jockey at Coolmore (assuming it was even available) as being anything different.
This new operation looks to be quite an interesting move – hopefully that means he will now be on Courage Mon Ami and will actually ride the horse a lot closer to the pace than he has been the last few times he has run.