More than a little, e.g. WRT the "traitorous eight" and California job hopping:
"I'm not saying California firms like it when talented employees leave with know-how acquired on the company's dime. But the broader ethos of the valley regards such activity as not only acceptable but essential to the economic dynamism of the region."
No, by long standing public policy (way before the Silicon Valley or even HP day) non-competes are unenforceable. Perhaps something of this ethos has developed as a result, but I'm sure the law came before the ethos. Well, maybe HP back in the good old days was relaxed about this, but definitely not Shockley the junk yard dog. If he'd started his firm elsewhere we very possibly wouldn't be communicating on this forum right now, because of how this would have slowed progress of the field.