Very plausible. OTOH,
"Mexicans are largely caucasian..."
The Spanish in Mexico are Caucasian (and inordinately proud of it) -- but they are upper class, and seldom become criminal invaders.
Those who criminally invade us by sneaking across our border are, in the vast majority, "Mestizo" peones-- predominately Amerindian -- and are dark and swarthy in complexion, with "Indian" facial structure.
Anyhow, I expect your "focus on the hypocrisy" is closer to the mark on the cartoonist's (effective) intent.