If the play results in 4th down but you are within field goal range, the logic will take the penalty if it pushes you out of field goal range. That would have been a long field goal, but it was close enough that the defense assumed it would have been attempted, and wanted to force back another 10 yards. That's a tough call whether to take the penalty or not, and you're probably not going to find a solid consensus among real coaches one way or the other.