I am not sure I understand what you are suggesting. It seems that amidst is only an information giving tool and not a tool which influences biome generation in the way you are suggesting.
AMIDST can FIND Biomes, it is just a insert Seed and get what the Map will look like Tool. He suggests 1. Generating the Spawn Continent and 2. setting the Worldgen to vanilla Amplified to generate the Second Continent. AMIDST just finds the Continents to help you with selecting the Seed.