You asked what I would do. I would do exactly what you did. Tell the person it’s a wrong term and it shouldn’t be used. At no point I said you should suck it up. You should correct the person and you did.

I don’t know what you mean by looking at you “inappropriately”. Like how? It’s subjective. You assumed it’s because they didn’t like your looks. But there’s no way to know

If you said hi and no one answered, it’s certainly rude and you’ll encounter rude people everywhere you go. It’s not something you can sue for or get people fired for not saying hi to you. It’s unpleasant but courses of actions you want to take are extreme.

Of course you can also quit your job because someone didn’t say hi to you or looked at you the way you didn’t like.