It is just the latest excuse of many. Obama is burying the US under a human wave invasion. He is replacing the population with one that is more compliant, dependent, reliably Democrat and which will assure perpetual leftist, big government rule (until the whole thing collapses).
It still doesn’t make sense, in a secular context. Mexico isn’t even a better place for Mexico’s elites, considering all the security measures they have to live under. So our “elites” want to turn the US into Mexico. It just doesn’t make sense. Unless you are the antichrist.