First do you have definitive proof the players are the age you have said?
Where do these conversation take place? I would like to hope the erp takes places in less than public chats.
If for example they are doing in guild chat and you might know you can not ignore someone with guild without turning it off. I would just troll their chat.
I am finding quite to believe kids would be into that but if thats what they want to do I wouldn't get in their way.
For everyone else benefit my server is a public one and everyone is welcome.
+1 to Exelenores reply.