I agree with that. I also think that if we're not gonna protect people from stuff like this, then we shouldn't have protected classes at all...
While I'm not sure I'd argue we shouldn't have protected classes, it is interesting to ask what the difference is between religion and political affiliation.
I've recently argued that there are no aspects of your sexuality or your personal beliefs that are choices you can make. You can decide what you're going to have for lunch tomorrow, but you can't decide that you now believe in unicorns, and you can't decide that you now have a foot fetish. These are not choices. Changes in personal beliefs and sexuality can occur throughout life, but they're not basic yes or no decisions that you get to make.
In that respect, you can decide to call yourself a conservative, or a liberal, or a centrist, or even reject ideology, but you can't decide to reject or embrace the values and concerns that are the reasons behind your political identity. Gun control, immigration, abortion, the environment, etc. You can't just simply decide to feel differently about any of these issues. It's not a matter of choice, it's a matter of belief. The question is, why is one form of belief a protected class, and another is not? I'm not sure I can properly answer that question.