I didn't mention anything about actually building the thing. I said they build a base on the planet to study* the structure, understand the ancient artifact. Just to clarify further, the pyramid was already there, on the planet, before the rebels came and occupied it. So all your points except one are invalid. And is that bad of an idea? Maybe an ancient civilizations whose history and existence was erased with time left the structure behind. Is it that implausible? And it was just an idea. I'm not imposing it on anyone.