I disagree with making "diversity" a goal. If the developers in a specific free software project do not include demographic D, I don't think that the lack of them as a problem that requires action; there is no need to scramble desperately to recruit some Ds. Rather, the problem is that if we make demographic D feel unwelcome, we lose out on possible contributors. And very likely also others that are not in demographic D.
There is a kind of diversity that would benefit many free software projects: diversity of users in regard to skill levels and kinds of usage. However, that is not what people usually mean by "diversity".
Common sense from RMS.
Looks like he was feeling left out.