Personally I would not work at a place which did so, and would consider reporting it to the anti-discrimination department in my country.
We (in the US), rather emphatically, do.
(There are some protections against religious discrimination in employment that apply to most employers, but those protections do not extend to prohibiting employers from all internal expression of religious views, or even substantive policy based on religious views. And, in fact, writing additional affirmative protection for employers’ internal expressiom of religious views, even to the extent of making that a basis for exempting them from generally-applicable legal requirements, is a popular trend in the US right now.)
Accommodating employees and their religious practices is another matter, within reasonable limits.
Most Silicon valley companies depend heavily on immigrant talent and resource pool to keep the perpetual billion dollar start ups coming every year.
If your political sentiments are in deep opposition to what brings in your salary, you already have a very broken view of your life in general. And a company executive expressing any sentiment isn't going matter much, if at all.
Companies are often intensely political; artificially pretending neutrality internally while actively working externally to influence the political landscape to me is more bizarre than being open about politics in the office.
If a corporation actually is solidly neutral and inactive politically in it's external actions, then, sure, the internal environment should reflect that.
> it's insulting to employees who may have an opposite position politically.
I don't see how that's any less true of a company's external political activism.