Quoted from GetTheJackpot:Farsight couldn't come to an agreement with him, haven't seen him in anything recent although imdb lists him as being active.
He did voice work for the Back to the Future video game a few years back. Telltale was able to use his likeness in the game and had him do a bunch of the voice. Not sure why Farsight couldn't make it happen, but I imagine it was more than they were willing to spend on it.