It sounds like he wants to be ready, but he's afraid. And that fear is keeping him from educating himself, and without education, you can't progress. It's good that he recognized a need (that resulted in a threesome), and knows you had a good time, and the jokes are his way of getting comfy with whatever the next step might be. Maybe?
It sounds like you guys will have a ton of work to do before your friend can be more than a friend. But it also sounds like you have a strong foundation and good poly intentions.