I don't know if I would call it a bias -- it's just a desire to have a place where lovers of traditional music can hear traditional music. Sort of like a bluegrass room or a songwriting workshop. Give a specific audience something they want to hear. Why would someone want to play a long dreamy ballad at a rap venue?

Contrary to what SOP or banjoman would have us believe, traditional music -- in all it's many forms -- exists as a thing separate from other types of music. "Singing and playing" is an activity. Saying that singing and playing is a tradition and therefore anything that gets sung and played is traditional music is silly. In fairness to SOP, I think he's seeing the interconnectedness of all music and the fact that every form of music has some sort of history behind it. I agree with that, but it doesn't stop me from hearing different types of music and being able to say, "that's a rock song, that's baroque, that's flamenco, or that's a traditional French dance tune".

I, too, don't like rules about music making. But not playing in a venue that's booking a style of music you don't play just seems like common sense.