He's extreme in following his dogma. If he believes "they" is plural in nature, he will refuse to use that as a singular - and that is not because he disrespects you, but because he thinks "this is the right thing to do".
If you believe it's fair to have a particular personality that requires other persons to call you "they".... doesn't it follow that it's fair to have a particular personality that makes you feel very bad about "misusing English"? It's really two sides of the same coin, if you believe a person has the right to decide what pronouns he's comfortable being called, you must also believe a person has the right to decide how he uses a particular pronoun. The essential thing here is that RMS doesn't avoid "they" out of disrespect, but out of his own particular weirdness/ peculiarity... something that we should be able to respect.