Why not? And are you claiming that this is simply a moral standpoint, or do you want to legally prevent employers from firing employees for off-work behavior?
Certain companies have been founded based on religious beliefs forever, that doesn't mean that it is morally correct for every company to have religious foundations. If you want to run your company that way, you're absolutely welcome to, but upon what reasoning do you claim it is wrong for me to act differently than you choose to?
> You shouldn't be fired for things you do and say outside of work, period.
Which would presumably apply to all companies. Under what ethical basis is this a good rule? What if I want to fire someone for what they did outside of work? Why shouldn't I be allowed to do that? Why should your belief about how you would run your company affect how I run mine?
At this point people are diluting the phrase "cancel culture" to mean "thing I don't like that is vaguely related to politics or political correctness". That's not a useful concept. It's just a thing to be angry about.