Why should they stay or be allowed to stay if they have more ties to Mexico than to the greater USA? They need to get over themselves and their "Mexicaness". I could care less about how many friends, relatives and business they have in Mexico. American security and sovereignty is more important
Advice:
Don't romanticize these Tejano clowns. I could care less about their heritage and they could care less about mine. They are either on board for a fence or not.
Your misunderstanding is terminal