I'm not in his shoes nor in yours but I think there is a scale for proprietary software, ie if you write server side, it is less enslaving than client side, if your product use open formats and allow users to go away with their data, it is better than not, etc.
(Secondary is, yes, his personal behavior. I don't make fun of him for his grooming or anything quite so superficial, but I think his behavior towards women in the tech community is notably not something to be proud of and his lack of common respect in other ways[1] is appalling.
[1] - "It doesn’t take special talents to reproduce—even plants can do it. On the other hand, contributing to a program like Emacs takes real skill." http://article.gmane.org/gmane.emacs.devel/36460 )
Slavery: It is a metaphor. A proprietary software handling my data, my content, my texts, my thoughts, my music or my relationships, and save these important personal assets into a format I cannot control, disallowing me to take it back in a useful way, is a kind of "ball and chains" that can be allegorically referred as "slavery": the user is losing important personal freedoms, most of the time unknowingly, or unknowing of the alternatives.
This is a(and I really hate this term) first world problem of the greatest order. "I can't use Facebook because it's proprietary and they're evil." So what? Just don't use Facebook.
At this point(and RMS and the FSF have been a major contributors to this, for which they should be thanked), users have a choice in the software that they use. They have the freedom to choose what they want, whether it's proprietary software, OSS, or FOSS.
Slavery doesn't come into this. You believe that a product or service doesn't respect your freedom? Don't use it, or use an alternative that gives you what you want. That is the choice that Stallman has helped bring about.
You're forgetting another first world problem that many people have: peer pressure. "What, you're not on Facebook? Lol, looser." Besides, with bullshit like the Facebook Login coming up, it's not unreasonable to assume that you WILL be forced to use Facebook for many things on the web. While I personally don't care and can put up with the peer pressure, other people can't.
And people ARE being forced to use proprietary software. At home, at work, everywhere, and if it's only because they don't know any better, or have been locked in by proprietary formats. You don't always have a choice.
Furthermore, it's not just about having a choice. It's about breaking the dominance, and eventually getting rid of proprietary software altogether. The only rational choice for any human being who's interested in progress and long-term sustainability is Free Software. Proprietary software is opposed to both of these concepts.
Weird worldviews will result in you be treated weirdly. Deal.
And people ARE being forced to use proprietary software. At home,
Change. If it's that important to you, you will.
at work,
Quit. If it's that important to you, you will.
if it's only because they don't know any better
Then they don't care, and it's unimportant.
You don't always have a choice.
Yup. Life kinda sucks, huh? Wear a helmet.
Furthermore, it's not just about having a choice. It's about breaking the dominance, and eventually getting rid of proprietary software altogether. The only rational choice for any human being who's interested in progress and long-term sustainability is Free Software. Proprietary software is opposed to both of these concepts.
This does not follow from...er...reality. Terribly sorry.
I write proprietary software (TEH HORRARS!). I am also interested in technological progress. The two are in no way opposed, unless as your postulate you take the really cretinous stance they they are--and once you do, well, sure, it's obvious. But that postulate is wrong and cretinous, so...
Speaking to pragmatism, Stallman has unequivocally said in interviews that if you write proprietary software you should quit your job because you are doing something unethical.
Now, I'm glad Stallman is around. The FOSS movement is, I feel, very important, and its important that FOSS exists. I don't wish that Stallman would go away simply because we do not share the same fundamental beliefs regarding software. I think that would be a loss. But I'm also glad that there are like minded people like myself who do not view a proprietary app as some sort of violation of basic human freedoms.
Just deciding that you disagree with some views that someone has and thus you stand against them entirely is a bit extreme.