He did seem to prove that man was good, and if given the choice, man will choose good. That's what the candidates proved.
Jack volunteering to be the new Jacob
Sawyer's constant selflessness
Kate caring for Aaron
Sayid saving them on the sub
Hurley has always been good
Claire and Charlie's love
Rose and Bernard
Desmond, where do I begin...
Even Linus made the good choice in the end and took the #2 position as well
the list goes on...
I guess MIB was wrong!