I sympathize with you, but even after all the messages here, I still have no idea what you mean by “rattle”. I assume it’s some sort of noise, but since no one here has heard it, it would be hard for anyone here to make a judgement as whether or not other Outbacks make the same “rattle” sound. What rattles to you might be humming like a kitten to me.
If that was my car and encountered the same responses from the dealer, I would have asked already to have them start another one on their lot or gone to another dealer to ask them. If that is not an option, I would not hesitate to flag down another Outback owner I see on the streets. Isn’t that your best means to compare and confirm the noise?