In the US? Would be protected free speech, and the government cannot make any laws about it.
For your company, though, they could fire you for violating their internal policies.
To categorize the speech, I would say it's just being an asshole. Even if you believe biological sex is assigned at birth and is immutable, going out of your way to not address someone the way they wish to be addressed is just being intentionally rude.
So is it okay that the company does not tolerate that view, even if that view is only expressed through speech? We're not in the context of a government, only an employer. Is that fine?
For your company, though, they could fire you for violating their internal policies.
To categorize the speech, I would say it's just being an asshole. Even if you believe biological sex is assigned at birth and is immutable, going out of your way to not address someone the way they wish to be addressed is just being intentionally rude.
But even then, it's still speech.