Those layers were deposited, lithified and then pushed up by continental collision. They did not have to be in a ‘plastic’ state prior to the folding - they were compressed and heated by the collision. And then eroded, and a sandstone deposited on top of the unconformity. No way a single geological event such as a flood can do all of that.
Funny how they eroded perfectly flat before the sandstone was deposited. Go anywhere in the world and you see flat layers, folded or not.
Whatever force folded those layers also reflattened them and the sandstone layer was deposited before any meaningful erosion could occur.