Whoever wrote the "rose-colored glasses" thing about INFPs was looking at us through some
I would have guessed he was an ISFP too, but after reading this thread, I'd definitely say there's little doubt he was an INFP. The idealism is too strong - he has to be an NF. He was not outwardly stylish enough to be an SP.
He was also a vastly better songwriter than musician or singer (from what I've read, actually quite poor at guitar playing in many people's opinions). An SP is usually good at technical skill and an NF is good at coming up with concepts. Sure, both can possibly be good at both, but since he was much more conceptual than mastered at a skill, I'd say INFP.