It's an interesting observation. Speakers of a language often (always?) have a strong feeling of what is right and wrong in the language, and this feeling is not usually formally justified. People just know how to speak right- and hearing an incorrect expression feels jarring.
Stallman has touched on something deep here, and although his insistence to pick at it is probably part and parcel of his personality, it is not an unreasonable insistence. Unusual use of pronouns is likely to make many people feel uncomfortable.