Also, like Jonas Grumby says, "Inner Light" looks and smells like a memory implant. Picard remembers the decades, but did he live through them? Or did ironweaver Kamin? For the first few days of the memory, Picard behaves like Picard - but for the following decades, we don't necessarily see him making any decisions in life, taking any action, thinking any thoughts - it could just Kamin doing the living, the thinking, the choosing.
I don't buy that it was purely a memory implant. To me, that would imply a passive participation in the download - watching events happen and moving through it as if you were watching a 30-year movie, from start to finish. I got the impression that he was always an active
participant in what was going on, as in what would happen to Picard if he was thrown into this situation and was forced to live it out. He was an explorer at heart, always venturing into the nearby mountains, a hobby that his "daughter" started to embrace once she became of age, many years later. This would imply that certain parts of Picard's personality and "original life" were always interwoven within the "new life", and not totally supplanted. Picard's scientific mind allowed him to see what was going to happen to the planet and its star. Ironweaver Kamen was likely nothing more than a construct in which to place Picard, to be used as a vessel to interact with everyone else in the program, that may or may not have been loosely based on real people. (It's been years since I've seen the episode, BTW, so my recollection of specific lines of dialog here are nil). He really could have done anything in that world, but he approached it as Picard would through the very end.