Maybe. He would be missing those important early years and would have to pretty much completely relearn the game. It is a lot easier to learn something the right way than to learn something the right way after the wrong way is so ingrained into you. It is not so clear cut as you take it.
Anyway, I have nothing more to say about the subject I think.
I view this more from the angle that when you play better players, you will by default, be forced to play better moves, so he played the moves that needed to be played.
If a guy plays a bad defense, you can't necessarily play the best moves from the strongest line you know against his bad defense. Your moves have to be relevant to the position he played. The game results might not look as pretty next to Kasparov beating Karpov in a hotly contested match, in which both players played each line, about as well as conventional theory had on record, but it was just as effective in the win column and gave a foundation for those modern greats. As I said before, it isn't Morphy's fault he played subpar players. That problem runs deeper than first meets the eye.
Morphy was the best there was in his day. I believe it is very possible that he had the potential to be the best in this day, too.
But, here is what I find most sad about Morphy...he "retired" from chess at a young age. So did Bobby. Somehow, I feel gyped.
From Wikipedia:
Returning to America in triumph, the accolades continued as he toured the major cities playing chess on his way back to New Orleans. By 1859, on returning to New Orleans, Morphy declared he was retiring from chess to begin his law career. However, Morphy was never able to establish a successful law practice and ultimately lived a life of idleness, living off his family's fortune. Despite appeals from his chess admirers, Morphy never returned to the game, and died in 1884 from a stroke at the age of forty-seven