Or maybe they have strong political views, but choose to leave them at home - rather than have conflict with their coworkers?

I know I personally have very strong opinions that I largely put aside at work.

Bingo. I'm left-leaning in a left-leaning environment, but I avoid talking about politics, especially in writing, because it can only hurt me.

Having lived here for the past few years, originally from the Midwest in an area much different than SF, my best take on the younger generation working in tech is that most do not hold strong views in terms of fiscal policies and generally equate politics to social issues. There is a fear of not being "politically correct" and offending someone. Most do not actually care and just lean with the side of least resistance.