Interesting read, fairly sure it's just one biased side of the story though, ultimately Yamaha had the option of Rossi, and in a choice of Rossi (even at the end of his career) and Spies there's only one sensible choice.
Spies didn't have a contract, and he clearly wasn't going to get it renewed with Rossi available/coming back, that's ultimately the reason why he left Yamaha...