People really do seem to forget how crazy the natural social separation is between the red and blue tribes is in the US. The CEO didn't really have to send an email for me to who they were voting for.
If you're okay with companies really obviously announcing their political affiliations in literally everything they do but not okay with companies being explicit about what everyone already knows then I think that says more about you than the company. Expensify is straight up not at all politically neutral, never has been, and doesn't really even pretend to. This wasn't a rogue CEO -- the employees voted on and helped write the email.