So many have complained about topics like this and thank you for your honesty, because to speak up about this is something that will make people more alerted. I myself also come across problems like this, but the only thing you can do is help people who are stereotyped as much as possible. You cannot tell the world what horrible things that person did to solve it, but the only way for people to solve their mistakes is to realize what they said and this is a common problem that happens: To defend yourself when you give rude messages or did something wrong, then getting away with it. I don't know what the actual reason is to being rude, because I have never been rude to anybody, ever.
If people will reply to you like that, don't be so weak to pull back and wing it. You have to go up to the person and tell them that what they said isn't to your likes and affects the image of your group. Letting the person go doesn't improve who they are, but worsen in their attitude that's why it's important for people not to continuesly do actions like this.
In the end, if they want to be the person they are, let them suite theirselves because when you're the ones warning them and they'll be the one to get the consequences. I agree with your post, but remember if you have things like this you must be stronger because the person who got away didn't benefit anything from what they did and you weren't any happier about it either.
I just hope this is understood. <3