The troll proposes to impose a 20% tariff on imports from Mexico.

If Mexico retaliates with a tariff on US grain, Mexican peasants might be able to prosper in Mexico. A side benefit for the US would be a big drop in immigration of Mexicans.

The US grain that won't be shipped to Mexico is grown by corporations, not by family farms. (The Republicans, under Reagan, destroyed nearly all of those.) So to hell with them.