If that's immortality then the Sith Emperor is just as immortal.
I never said he wasn't. The poster I was quoting worded it like the Emperor was immortal but Sidious was not. The Emperor was indeed immortal. As was Sidious. Note in my quote I said "As well."
It would be overwhelmingly foolish to claim the Emperor in TOR isn't immortal when he's managed to live for over 1000 years. Likewise, it's foolish to not consider Sidious immortal when death doesn't end him. He can even transfer his essence AFTER death. He doesn't even need to do it before hand.