I'm sorry, I'm speaking from a point of absolutely no experience in these high-profile Silicon Valley jobs, but "companies refuse to hire Google employees" strikes me as a statement akin to "the king refuses to dine from a 99.999% gold plate because they skimped out on getting him a 100% pure plate". Even right now, many tech workers see Google and other big-name tech companies as basically the ultimate goal of their careers, and I can't really imagine the kind of a one-in-a-million company that'd be justified in turning down a Google ex-employee based on just their employer.