What do people think of Peter, Paul and Mary's cease-and-desist letter asking the National Organization for Marriage to stop using their song?

I was wondering what people thought about this response…whether they feel it is appropriate in tone, whether more needed to be done, etc. It would be great to hear people on both sides of the marriage-equality issue. The letter can be found here if you haven’t read it:

http://prop8trialtracker.com/2010/08/27/peter-paul-and-marys-cease-and-desist-to-nom-stop-playing-this-land-is-your-land/