Stallman doesn't really have a coherent ideology. If you start pulling at the thread of logic for a bit, it comes apart like a knit sweater.
People make a name for themselves by taking a strong stand on something, no matter how unpragmatic or unrealistic (and therefore, in my view 'wrong'). I don't doubt that he is intelligent, principled and abides mostly by his dogma (or at least thinks he does), or that he is isn't sincere. Obviously he's made some good contributions as well and so has kind of earned the right to have an outsized opinion. Nor do I doubt that it's important to have a variety of voices on such matters, and that often points raised by these types of people are important for us to consider.
BUT - it's best not to engage these types on ideas because it's really about dogma. It's best to grapple with the psychology of such people, why they chose to be who they are, the self-identity they derive out of having such positions etc..
In a way, these types often serve as good 'devil's advocates'.
If they were even in charge of anything it would be mostly destructive, but they can contribute a lot by challenging accepted norms.
You have to take these guys with a few grains of salt.
In much the same way, in politics, you see some opposition antagonists with some good ideas, representing underserved groups. Though they would make terrible leaders, their opinions should be noted, I think.
For example, I'm not worried about Skype at all - but I was not aware of some of those finer points, and they are worth knowing about.