> If someone can't state their point without warping the very language they use to support their point, it makes it very hard to feel like anything they're saying is credible.

It's a bit of a long read, but David Foster Wallace's Tense Present[1] proposes something about language which I believe to be true. Wallace proposes that language communicates two things: 1) its direct meaning, and 2) the membership of the speaker/writer in a discourse group--that is, a community which uses a specific dialect. I think that your reaction to Stallman's choices of words is not to the direct meaning of Stallman's words, but to the communication of Stallman's discourse group. He's using a dialect, one which he had a large part in creating.

I don't think you can argue easily that Stallman is using the word "used" incorrectly in this writing, but it's easy to see how it's offputting and even a little insulting. And more importantly, it's exclusionary--when Stallman uses a dialect that we don't use, he's establishing himself as being in a different discourse group of which you and I are not a member. Or to put in your words, he's preaching to the choir. It's normal for humans to react negatively to being excluded in this way.

But the flipside of that is that specialized dialects serve to elevate the discourse of a discourse group on topics that interest that discourse group. There are rumors that Eskimos have X > 10 words for "snow", but we can observe the same thing in dialects of English: Medical English differentiates between a break and a fracture and borrows frequently from Latin, Programmer English uses "tree", "heap", "loop", etc. in ways that non-programmers never use them, Psychology English has specific meanings for "narcissist" and "OCD" that differ significantly from their usage in other English dialects. These differences are exclusionary, but their purpose isn't exclusion, it's as a shorthand for complex ideas that otherwise wouldn't be pragmatically possible to express in other dialects of English. It's not just preaching to the choir. These dialects were created to allow specific and accurate communication of the ideas of their discourse group.

I think that, at some level, that's what Stallman is trying to do. It does come across a bit heavy handed: while most dialects occur organically to meet the needs of their discourse groups, Stallman's dialect is to some extent synthetically created by Stallman. But Stallman's dialect does, to some extent, meet the needs of a discourse group. I, for example, find it very useful to differentiate between Free (Libre), Free (Gratis), and Open Source. These aren't differences which can be talked about as succinctly without Stallman's dialect, but they are differences that have deep implications for our society.

I agree with you that this usage of language is apt to alienate people who aren't members of Stallman's discourage group (or in your words, alienate his non-choir audience right out of the gate). But the same can be said of other dialects: Feynman, for example, talks about how Physicists start by teaching students models which are fundamentally incorrect, and iteratively change the model until the student understands a model closer and closer to the truth[2]. I'm not sure Stallman understands the implications of his jarring use of language for the uninitiated, and I think he would be more effective if he shifted his dialect to match the discourse group of his audience.

However, I do think Stallman fills an extremely valuable role by defining the language of this discourse group. There are many advocates of Free (Libre) Software who use more accessible language when talking to a more general audience. I like to think that I'm one of them--I've adopted a bit more of Stallman's dialect for this post than usual. But when talking with members of Stallman's discourse group I shift more toward Stallman's dialect, and this elevates the conversation. There are lots of people effectively advocating Free Software, but there aren't many people contributing to the creation of a dialect around Free Software.

It's also worth noting the level of control that corporations, politicians, and other political organizations exert over the dialect you're using. I'd posit that the dialect of English you are comfortable with using makes a distinction between "user" and "used" that is not representative of the phenomena those words describe, and that is largely because of the influence of the dialect Wallace calls "Advertising English" on your own dialect of English.

[1] http://instruct.westvalley.edu/lafave/DFW_present_tense.html

[2] I think this is described in Surely You're Joking, Mr. Feynman, but I'm having trouble finding a link; anyone care to help?