"Some songs are made unwelcome and that is not right."
You keep making statments like this. Please give an example.

"Songs should be presented in an environment where they can be viewed as art without being extended by political statements."
Why??? You make this sound as this is the only way songs should be presented. You completely miss the history and reason for the songs existence.

"In a recent radio program on the bbc it was recognized thoroughly that the folk music movement of the 60s and 50s was co opted (I believe that was the term) by the liberal left."
IF that is the case - so what? IF you look at folk music from the perspective of an ethnomusicologist, the music exists to suit the purposes of the community. YOU CANNOT CHANGE THE WAY A CULTURE DEVELOPS THEIR MUSIC. Simple fact.   You play ignorant to the fact that the folk revival had roots in a conservative movement, and the fact that it evolved with a liberal bent is merely the reaction of the culture and the times.   YOU CANNOT CHANGE HISTORY.

"it would be a good idea to keep the folk music world as open politically to differences as it is to different cultures."
You fail to recognize that folk music DOES recognize different cultures. Perhaps it is time for YOU to realize that there are different cultures that do not think the way they do, and you cannot alter their music.

"After all go back far enough in any culture and you will find something that distresses you. If we can have cultural diversity represented by flawed humans we can have political diversity as well."
There you go again - twisting reality for your own purpose.   Of course you will find something that distresses you in any culture! There is political diversity.

The biggest mistake in your entire way of thinking is that you fail to recognize that PROTEST music is about PROTESTING. In order to PROTEST, you have got to have a reason. IF you have a reason, then you already have an opposing opinion. You entire argument crumbles on the fact that you fail to recognize the folk music community arose because of the very repression of ideas and cultural diversity that you are attempting to claim they now ignore. That is pure bullshit. If you have an opinion, put it in song. If people do not support it, that is not the fault of the culture - IT IS THE CULTURE!!!