If he knew Crist was coming back into the game I agree that it was a poor decision to go for 6 at the end of the first half. But It doesn't appear that they expected to have Crist back on the field and ND hadn't gotten into the redzone since the first drive of the game. Chance to cut it to 1 score with UM getting the ball back to start the 2nd half, he had to try for it.
Niko Porikos grew up in an NTDP billet home. Cool story.