What? No, I'm not moralizing, I was talking about my interpretation of the ending. I think the post-credits tease is a flashback still, because giving a dude who (if it's real at that point) burned down a building full of people to prove he hated indians a ~happy~ ending runs counter to the point of the game.
To truly be washed of his sins, Booker had to be baptized to death, yo. He had to cease existing.
It's not our Booker DeWitt. It was another alternate reality showing what happens now that the Comstock timelines are gone. No one comes to take his daughter. So he doesn't cease to exist, only Comstock.