The proposal it not that the government "be ruled by science" at all. The proposal is all three branches of the government still exist. The legislative still makes the laws, the executive still runs things, the judicial still interprets the laws.

It's just a question of wedging in a small check and balance that most of the time does nothing, but who can intervene, in TBD ways, if things go gonzo bonkers. Have you seen Handmaid's Tale? The religious right is not far from that. We don't want that.