I think their thought was to have the middle of the field open for a shorter FG try. But it was dumb. :21 was enough to run a play for a possible TD, and if you don't score, spike it and kick. It worked out OK but :21 was definitely enough time to run a play, fail, and still get a FG. There was a probably a matchup they were hoping to see at the line of scrimmage and go for the TD if they got it.