He's a monumental figure, working for something extremely important, and surrounded by people who are very wrong. While Nader is much less respected than Stallman, the magnitude to which their respective fields are ungrateful for their respective contributions is about the same. Stallman's contributions I would argue are much bigger than Nader's. Come on he invented the OS that is now the basis of the majority of internet business. I think he deserves a little more respect for that contribution. If Nader had done something equally big in his work of keeping rogue corporations in check, we would have gone on a more Canada-like path than the Reagan-led path of decline that we did go down. Free Software has become a major force that continues to grow and improve our lives. Nader's contributions were not lasting, and have mostly been reversed by decades of corporate think tank astroturfing and lobbying that has whittled away the rights and protections of individuals.
You contend that the creation of the GNU utilities -- differently licensed but by and large feature clones of an existing software package was a more important contribution to society than the American automobile safety regulation changes brought about by http://en.wikipedia.org/wiki/Unsafe_at_Any_Speed ? Don't forget that BSD was already walking a similar course by that time. Emacs is pretty important, as well, but I think it ranks behind the GNU utilities, as well.
I haven't really tried to contrast them before, honestly, but I don't think it's quite that cut and dry.
