Russia stealing wheat from its farmers, and later the land as well, is no reason to pass laws forcing private individuals and companies to only sell the goods to Americans.
You have completely confused freedom with communism. What you propose is the very thing you seemed so troubled by.
It will happen that another nation will buy our food crops right out of the fields. The crops will be shipped where ever and Americans will starve. That is the point. Are you fine with this happening?
During the second world war there were shortages of gasoline, sugar, shoes, coffee, grease, etc., there were collections of metals, scrap iron, Rules were set in place and rationing stamps provided to limit a person's purchasing power. A nation does not sit and let there food all leave and starve all the people. It could happen. As I mentioned it happened in the Ukraine.
This year there has been a serious drought and the corn crop has been greatly blighted. As a result gasoline is up, many, many food items in the groceries are up and there is a shortage of corn products. Tortillas, etc. It does not make sense to use our food to make ethanol. It is not good for the car engines, etc. It is complicated ... yet we must look ahead to how to keep America a great nation. I am not Communist nor do I like or believe in Communist forms of government. If you want one move to Cuba or Russia. God bless America.