Yeah, same feeling here as well. In his otherwise excellent book Shoe Dog, Phil Knight spent a paragraph talking about Rob Strasser, an early employee who left for Adidas, and about how it was a breach of loyalty.
Did you skip the middle of the book? Those two people went through a lot together, especially within the forum of facing-off with their competitors, one after another. Guy was integral to Nike and ultimately he chose to work for the "enemy." Think what you want, but either Phil Knight was too much of a douche for too long, which wore him thin, or he stabbed his boss in the back.