Well, I don't want to bicker, but I don't think that giving this fellow another chord or two is really going to change his situation. But reexamining WHY he is in a rut, and giving him a roadmap out of it, just might help. It's the old thing about giving a hungry man a fish vs. teaching him how to fish. We all have our approaches to helping our friend out of this dilemma -- this is mine. Sure, I could send him off to learn "I Got Rhythm" and all its I-VI-II-V progeny, but I think he'll be better served by using his ears to expand his horizons.

My final suggestion is that our friend should listen to ALL the advice he has been given, and then go try it out and see what works best for him. Let's not argue about whose advice is best; I'm sure we all have worthwhile suggestions and perspectives based on our own experiences. Learning music is not a one-size-fits-all process; while there might be some good universal advice out there, a lot of this comes down to individual learning styles, goals, and experiences. I'm sure our friend can benefit from what both of us have suggested; to go back to my shopworn metaphor above, the hungry man benefits both from the fish you give him, and from the fishing instruction I give him. Can we leave it at that?