I don't recall what the specific thing was that ticked off the UND fanbase about him in 2016. I know he was playing games saying that Anas wasn't gonna play all week (somewhat expected with an injured star player the week of the big game), and then put him out anyway to get injured multiple times during the title game.
But yes, regarding your comment about TH. TH said Pecknold is the only opposing coach he's ever dealt with that refused to do an interview with him.