Re: Fatal Flaw?
Exactly. The decision of the protagonist in the last three minutes doesn't define his role in the story for the last two hours.
Also, to assume Rick is the protagonist only if he gets the girl is to say that you can only have happy endings in films. So Woody Allen wasn't the protagonist of Annie Hall because he lost her, and Julia Roberts wasn't the protag in My Best Friend's Wedding for the same reason, not to mention every romantic tragedy (which Casablance falls under) where they don't end up together.
I get it that WWII is a big event, but it doesn't make it the main story of Casablanca. It's like saying that Titanic is really a story about the people who told the ship to go faster vs the people who said it wasn't safe because of the icebergs. Jack and Rose? Not driving the action of the movie.