Ha ha! So the message implied is that if you oppose Mexicans taking jobs from Americans, you might be "mentally disabled". 
I think most Americans are in favor of Mexican immigrants, if they come legally. If we adhere to the rule of law, it is natural to oppose illegal immigration. I also think that most Americans would like to see that jobs are filled by those here legally, whether born here or naturalized. I realize there is the old argument "They only take jobs Americans do not want." I'm sure there is truth to that, but it wasn't that many years ago that young people took those jobs, picking fruit, processing fish, etc. Society has made it too easy for people to not work, and that should change. Any work is noble.