Because Yoshi-P is generally pretty in touch with the community and Kylin has talked to devs so they know Balmung is an RP server. On top of that I don't think they would designate a new server as they aren't available to Legacy players and they LOOOVVEEE their legacy players. It seems the easiest thing for them to do would just slap "RP" on Balmung and call it a day.
BUT then again it is SE so...
BUT then again it is SE so...