I have been actively participating in political discussion on the Geron board since 11/04. It is only recently that the abuse has gotten out of hand. My political posts have been less frequent recently than in prior months. I don't think the level of abuse over there has anything to do with what I post.
I also don't think my posting over there has any effect on Yahoos numbers or the number of posters over here.
Many of those missing Yahoo posters are those that I had reasonable political discussions with, so again, I don't think my posting over there has any effect on anything.