Meh. I appreciate echoes in the films. This is something different. I think it would show cunning for Palps to be able to have planned for his potential death on the Death Star. Catching an air grate is cheap.
Although we most likely won't find out how he survived within TRoS itself, I highly doubt it's as simple as you're trying to make it sound.
And my broader point remains: Star Wars storytelling is and always has been cyclical, so Palpatine surviving the destruction of the second Death Star and being thrown down a reactor shaft is both plausible and has precedent within the franchise.