But it’s stipulated that the predictor did put a bomb in Left. That’s part of the scenario.
This is instead part of the misleading framing. Putting bomb in Left is actually one of the situations being considered, not all that actually happens, even if it says that it’s what actually happens. It’s one of the possible worlds, and there is a misleading convention of saying that when you find yourself in a possible world, what you see is what actually happens. It’s because that’s how it subjectively looks like, even if other worlds are supposed to still matter by UDT convention.
This is instead part of the misleading framing. Putting bomb in Left is actually one of the situations being considered, not all that actually happens, even if it says that it’s what actually happens. It’s one of the possible worlds, and there is a misleading convention of saying that when you find yourself in a possible world, what you see is what actually happens. It’s because that’s how it subjectively looks like, even if other worlds are supposed to still matter by UDT convention.