Legally documented immigrants are often considerably more strict and harsh in their views on undocumented immigrants. A very "I did it right and so should you have too" mentality. This is particularly strong among refugee immigrants (Cuban and Venezuela, for example). The problem here is the perception that undocumented immigrants are all members of roving street gangs selling drugs and murdering an raping. Farm hands and construction workers can get documentation that passes the checks required of employers. So they weren't expecting their own employees to be swept up in it.

They're not stupid, just heavily propagandized to where they need to experience personal consequence to reconsider. It a perfect chance to have the conversation with them to win them over.