In the press conference Felix stated that he pulled at 5200 feet, which was the planned deployment altitude (well, 5000 was planned, but the 200 feet difference is negligible at 170+mph).
So that solves it then. That would mean that he did not pull early to preserve Kittinger's record as many people were suggesting. He simply was going too fast and Kittinger had gone too slow (especially because of the drogue).