he is... the free software movement fails without the hearts and minds of developers. Developers are, unfortunately, still humans and will refuse to follow the advice of someone they deem to be a twat. Even if that twat is right, if you can't convince someone free/open source software is better you lose.

Stallman is well known to act like a twat, thus holding him up as the voice of foss will convince people that foss is just a bunch of douche bags. thereby damaging open source.