If open-source projects adopt an "email first before pull request" approach, I think that's a big mistake. That will mean a lot of dialog with people who aren't actually going to do the work, and a lot of missed patch opportunities from people who have done or will do the work but are put off by the uncertainty of a policy like that.

Regardless, if a pull request is the wrong vehicle, then the correct response isn't, "Request rejected! Go away." It's "Let's talk about this more." It was a two-line change that made the project better. (At least, nobody has so far claimed that the gender-exclusive language was better.) I think that's enough of a positive signal to be worth following up on, and certainly not the dire insult that some believe it to be.