I have perspective on Big Tech and politics. This perspective comes not just from personal knowledge but also from talking to actual tech billionaires in VC and other areas, not just ordinary techbros and run-of-the-mill engineers.
First off: I don't believe anyone who says "Commiefornia is such a one-party state that no one at the top is anything but a leftist." This is so untrue I can't even wrap my head around it but I can only imagine maybe a person saying this just either hasn't lived in California before, or has lived in some very midwit parts of SoCal which are actually really like that.
At the VP and above level in tech companies, politics isn't all leftism, all the time. Not even close. There are Cato Institute libertarian types and paleoconservatives everywhere, people whose conservative "trad" outlook drives a huge amount of how they run their family life and how they donate to causes.
What you see almost none of is the newer strain of "god, guns, and gays" religiously-based conservatism. That's totally lacking. The conservatives you meet in Silicon Valley and SF are money conservatives, not social conservatives. Everything is down to economics.
So why, all that having been said, are they on the side of the left whenever it comes to diversity, equity, and inclusion?
It's simple: their data tells them it's a good idea from an HR standpoint.
Employees who like each other too much are bad for business. You don't want a whole department of employees to think they've got so much in common that if you fire one, they'll all quit. You don't want people being comfortable enough with each other to discuss salaries. You don't want them to find out they all share complaints about management and working conditions.
How do you keep people in the same department, even the same exact position, from realizing they have more in common than they have different? Enter DEI. When Whole Foods used big data to evaluate what made stores less likely to unionize, right at the top of the list, there it was: diversity initiatives. We only know that because one of their employees leaked the information from a presentation where diversity was actually presented directly as a union-busting strategy.
If you think the guy next to you is either a white supremacist keeping you down, or a race-baiting quota-filler likely to slap you with a harassment suit if you make the wrong joke, you're not going to talk more than necessary or start a deep friendship that gives you the ability to have a united front when negotiating. The very concept of sharing salary information is a minefield if you're steeped in the identity politics narratives.
These programs work to keep employees suspicious and untrusting of one another. They also make everyone think that everyone believes in an idea that only a few people actually believe in. The rest are just saying what they think will keep the mob from turning on them.
This is also why the Democrats have zero pro-union, pro-worker stance left. These diversity strategies were constructed by business consultants to drive business outcomes, not to help workers, so when Democrats adopted these tactics, there was no way to hold pro-worker views in tandem.