That definitely breaks rules and should be punished (a warning point atleast), so in my view it should be reported to one of Moderators, but I am not exacly sure if they are solving such things.
So a report player tool could be quite useful here. I'd to see a official statement concerning this problem.
And here some of rules:
Global Rules (May Apply In-Game!)
1. No Inappropriate Content
This category includes, but is not limited to, content which is:
Vulgar or graphic
Disrespectful
Offensive to any specific group of people (Racial/Ethnic/Country-based)
Offensive to a general audience
Obscene
Threatening
Insulting or calling out another member (Cynicism may also be seen as insulting)
Relating to drugs or activities involving them
Invasive of one's privacy