I think the point is that Apple didn't treat Safari/Webkit as being a competitive advantage so much as nullifying a competitive disadvantage -- it was a defensive play, not an offensive play. (A nice analogy is Android, which Google developed out of fear they would miss out on the mobile market rather than out of any desire to "own" the mobile market. Google didn't want Apple or anyone else to own its destiny, just as Apple didn't want Microsoft to own its destiny.)
