Iffy situation, given the Seattle D's ability to stop big plays. Coach trusted a long shot from his kicker more than the O's ability to get five yards in one play.
To peel the onion a little further: Did the OC have a play that he had confidence in, and players that he had confidence in to run it, that would get you 5+ yards?
Miss the 5 yard play, game over. Miss the field goal, a chance to win, game over. I can understand that. The three previous plays netted only a total of five yards and were probably his best do-or-die calls. Still, beyond the kicker's tested range, I'd rather go for it. Better to give it your best shot in defeat than to let your offense feel the sting of surrender.