The book actually comes to pretty much the same conclusion: it would have been extremely difficult for any leader in his position to retain Nokia as major playe

The book actually comes to pretty much the same conclusion: it would have been extremely difficult for any leader in his position to retain Nokia as major player in mobile phones, and there's no evidence that Elop was a Trojan horse etc. That said, he did make a large number of unforced errors, mostly notably the Burning Platform memo, which accelerated the decline.