Same reason that I want to use the word "sandwich"
If you want to disagree without being disagreeable, that's you. But if I choose to be disagreeable about it, I don't see why anybody should have the power to stop me.
They can want whatever they want, but they cannot force people to be polite.
Then you need to prove that using the N-word equates disorderly conduct.
Hint: Just because someone uses language you don't like, it doesn't mean they are being disorderly. The way I see it, you simply don't like it when people use racial slurs, so you use a flimsy excuse (aka by calling it disorderly conduct) to shut them up or kick them out. This is a tactic very frequently seen with the Left.
You can ask, but you cannot demand. And if I still want to swear? There shouldn't be any damn thing you can do about it.