Because they won the game. It's a pretty simple reason.
This was all covered yesterday ad nauseum. I would have run for it on 4th down but after thinking through it I understand his thought process. And it boils down to exactly what he said: field position. Everyone wants to ignore the giant elephant in the room: weather conditions. They had gone for it I believe twice on fourth down and come up empty. So his view in a game like that is field position was paramount. Pinning them down in their end opens up possibilities of a safety, and gave you better field position. Just less than half the time in OT was still on the clock. You stop them deep, you gain field position when they punt. Puts you in a better spot to win.
It took them two series to stop them vs. one which affected what they had to do to pull out the win, but that doesn't change the logic of the decision. As for them being lucky, the QB made an excellent throw and the WR made an excellent catch. Then Richie made a great block and Shady made a great run. why is it when the Bills make great plays they're lucky but when other teams do it they're great plays?