I don’t think it’s referencing anyone in particular. It’s just common for US politicians to be creationists or idiots, or both.

The whole fossils in the mountains thing is how creationists explain dinosaurs through the flood/Noah’s ark, since they believe earth was created 6000 years ago.

The term you are looking for is “Young Earth Creationism” and a very significant amount of religious people believe it to be fact.

No one is saying mountains aren’t real - that’s an example to show the absurdity of denying facts. The person referenced is a “creationist”, and probably doesn’t reference one specific person. The biggest thing with creationists is denying evolution.