"Misgendering" is a human right.
Despite it often being equated with "sex" by lazy thinkers, "gender" is not the same thing. In fact, it's not even in the same conceptual framework. "Sex" is a term used in the context of biology, "gender" is used in the context of grammar. Although most often used as a grammatical shorthand for "sex", "gender" simply means "a class of objects differentiated from others" That difference could be sex, but it could also be age, nationality, color, or any other distinguishing feature.
Now remember, language is a social construct. Words mean what we as a society agree they mean, otherwise communication would be impossible. But just as no one person has a veto on what a word means, no one person has a veto on what gender you may assign to someone. These are your words, as long as you make yourself understood, no one has a right to deny how you use them.