I don't think that's true (in fact has been disproved often, e.g., Reagan), and if the assumption is not true, then Rubin's whole argument falls apart.
If Ted Cruz doesn't become president, it won't be because of independents, it'll be because of the GOPe.
True. I'm an Independent, but that is because there is no Constitutional Conservative Party, not because I am a moderate.
I really don't believe there is a wide middle of truly independent voters anymore that vote R sometime and D sometime. I think it is all about turnout.