The odds were against him, but Belichick gambled and it paid off. After Lynch ran to the 1 there was still over :50 left. Many on message boards and twitter were screaming for him to take a timeout so Brady and the Pats could have a little time to respond. But instead he let the clock keep running which I think caught Seattle off guard and with just one timeout of their own they were likely going to have to pass on either that 2nd down play or 3rd down. Since the Pats kept their goal line defense in Seattle outsmarted themselves by trying to pass on 2nd down rather than run and risk not scoring and then being forced to use their final timeout and also be almost forced to pass on 3rd down with the Pats expecting it.
If NE had called timeout right after the Lynch run to the 1 it would've ensured the Pats offense having some time if needed, but it also would've left the Seahawks with time to run on 3 consecutive plays if necessary. I think running on 2nd, even a read option was the best choice but I do see some validity in trying to pass while NE was in the goal line run stop defense and with Seattle only having 1 timeout left. As it turned out they played right into Belichick's hand.