Interesting assertion. Honoring the distinction between “open source software” and “free software,” it seems that a nugget like this should at least nod to the precedents on the East Coast. If only because the citation itself makes the geographical distinction.
Lisp Machines vs. Symbolics in 1980s Boston essentially formalized free software. And Brewster Kale asserts that this is directly related to changes in the US copyright act. Which is a nod to the interplay being highlighted between law and software.
There was also the older precedence that goes back to the IBM SHARE groups. All this was open source. Not in a contemporary sense, but it was certainly true in a literal sense. This reality can be attributed to either the way business worked at the time or looming antitrust threats. Again - regulation and software.
Not picking apart the highlight posted here. Just attempting to add additional context to this idea of “Silicon Valley” which may not be so geographically significant. But the interplay between larger social structures and software is absolutely spot on.