Playing music has nothing to do with RP. Now if someone puts on /rp and starts going off in chat about some made up story about their origin and their history, now that is RP.
...and is neither forbidden nor punishable on a server that ISN'T labeled RP, whether it's Brandywine or no. You might get trolled, or ignored, but you are free to do it.
RP servers are simply a place where you're more likely to find someone to RP back.
Also, the idea that the server should boot F2P people to make room for VIP is a bit abhorrent, even for a Lifer like myself. AFK, maybe, but if someone is actively playing the game, there's no reason to kick em for little ole me.