He’s just a crusty old asshole who hates everyone, and ND obviously is polarizing.
But his hatred specifically with ND goes back to him being the DC at Michigan St.
In 2013, when MSU finished 13-1, and won the Rose Bowl, with their only loss being against ND.
The Narduzzi Defensive scheme is to put your corners on an island, have them grab, hold & tackle the receivers at the LOS, & force the official to make the call.
It worked for him all year, but against ND they got flagged for multiple PI’s (and they all were).
He lost his shit over it & says the refs were ND-biased, despite the fact the refs were B1G refs that MSU brought.
He was always bitter towards ND, but since then he has been butthurt.