“Neville, about sukkah on Shmini Atzeres double-check your Halochic facts, ok? It is a chiyuv.”
How can it be both Sukkos and Shmini Atzeres at the same time? The reason we don’t take arba minin without a bracha on shmini atzeres is exactly this reason. The only reason it’s ok to sit in the sukkah is because it’s something one might do anyway for pleasure.
You’re actually just wrong on this, so I don’t know why you feel like speaking with such confidence.