IMO it would show exceedingly bad judgment to ask someone how they voted in an interview. I wouldn’t categorically refuse to hire such a person, but it would be a strike against.
I understand that perspective, but it doesn't affect my position. I'm free to choose who I work for, and I wouldn't choose to work for someone who found the question disqualifying. I get to define my own utility function.
Sure, you're free to choose your employer however you wish, and there are plenty of tech companies whose executives didn't vote for Trump.
But you may find that many executives — including those who did not vote for Trump — are not interested in hiring people who believe they are entitled to know how their colleagues/bosses voted.