Where does GP advocate for this? As I read it, he is saying that there are some potential bad hires from lower tier schools that should be avoided. I don't think this involves 5 schools or GP's hiring history.
They said that there 100 bad hires for every good hire while by omission claiming that every Stanford hire is a good hire... But also that you should definitely be hiring talent 'on it's own merit'.
I feel pretty comfortable with my interpretation.