In a sane world neither should be fired for expressing free speech even if it is vile.
Let me also point out there is a difference between being fired and being arrested. Even so, free speech is not an absolute right (e.g., erroneously shouting fire in a crowded theater).
But, yes, it is a slippery slope.
I call it free speech from a barstool. Yeah, you can say it but you’re likely to get knocked on your ass for it.