That simplifies the issue then doesn't it. The migrants need to apply for asylum in the 1st safe country, which would be Mexico. No need to enter USA period.
Exactly -- immigrants fleeing "unsafe" countries are required to file for asylum in the first safe country they reach -- which would be Mexico. The U.S. should enforce this. All immigrants at the southern border should be denied entry and told to file for asylum in Mexico (meaning they need to file to stay in Mexico & not come to the U.S.).
Unfortunately I don't think Mexico will support this. The country does not want these migrants and simply wants to see them go into the U.S.