Being "out of touch" with "the white majority" (or anyone for that matter) is fine by me, if it means being able to have nuanced and rational opinions. (Unlike Trump's broad brush statements.) Furthermore, your argumentum ad populum doesn't make Trump's statement any more just or accurate.
Just out of curiosity, what do you think about "that point"? Do you think the Mexican government is pushing large numbers of drug dealers and rapists into the USA? Do you think this is an issue important enough that it should be a major part of a would-be president's campaigning?