It seems to me that several issues are becoming entangled.

1. Is RD a racist? So far probably not, although perhaps unwise in choice of words on one occasion (and who among us can say we do better than that?)
2. Accordingly the OP on the thread on Facebook was probably a shit-stirrer, maybe even one from the BNP hoping to handicap FaF.
3. If he is, so what? This is difficult. I would certainly not knowingly suport the use of a folk festival as a platform (even indirect, if for example the loathsome Griffin might be able to say, if David Hannam played Cropredy, "Our members support traditional British music and play at traditional folk festivals") for the BNP. However, if we blacklist people merely because they are members of a political party, are we not as bad as Senator McCarthy was? - Incidentally I put my words badly in this area, previously. But where to draw the line? I would want an undertaking not to sing anti-abortion songs, and while I find some of Bellamy's choices from Kipling tastless in the modern world, I think they fall on the right side of the line. Organisers - it becomes harder. What if Nick Griffin was an able interpreter of traditional folk song? I would bar him because his singing would not be separable from his propaganda.
4. Joe. I think Joe has as much right to post here as anyone else, so long as it is clear that he does so with his personal hat on and not his mod's hat on. I think he is overdoing the right to shout "fire", but I would support his liberty to say what he has.