"Don't implement pull requests because it is much nicer than Linus' solution, so if you implement it then everyone's going to want to use it and then when you insist on not using it no one will want to play with you. :("
Seems a bit like a flawed argument to me.
Or how about:
Progressively enhance the AM protocol so you can receive both basic AM requests from non-GitHub users OR produce a great UX (as it currently is) if both users are on GH.