Nori is a subtle card. When it comes to Dwarves and Spirit, most people look at Óin for access to as well at a minus 1 threat cost. But what you get with Nori even after his errata, is a dependable and reliable hero who can defend early attacks and chip away at your threat every time you play a Dwarf from your hand.
It may not seem like much, but over the course of the game this can easily be 5+ threat. He's also in sphere to give you access to actual threat reduction and Dwarven resource acceleration via Zigil Miner. So if you were to play a Zigil Miner from your hand you gain resource acceleration to play more Dwarves and a nice threat reduction. Double win. No wonder he's so happy!