If people want to use offensive marginalising language there is nothing stopping them, but, you have no right to expect others to agree or not call you out for your dickish behaviour.
And that ultimately is the paradox of the anti-pc brigade. They want to say what they want in the name of free speech but restrict the freedom of others to respond.
Free speech is about expression of ideas not vocabulary. You can talk about black people without the n-word, you can talk about the disabled without terms like cripple, your expression of ideas is completely unrestricted.
The fact is that meanings and connotations of words change over time. They always have and they always will. We gain nothing by kicking against such inevitability.
Discouraging use is not prevention of use.