I am confused. I don't see "dry" entering into it at all. SER is a wet location wiring method and conduit does not make anything dry (you can't use a dry wiring method in a wet location and say it is dry now).
The conduit is mainly for protection from physical damage. As long as you follow the Romex rules about setback from the face of framing members in the ceiling I agree that is not subject to damage
All that said I do not see a problem with your plan.
