firstly, he said hes Mexican 'and proud of it'. Its one thing to be Mexican, its another to be a Mexican demoocrat who is openly proud of his mexican roots, and is part of several mexican oriented pressure groups. So that makes sense he is not impartial.
secondly, he was called a racist since last summer, and that example you gave is very recent. The other things he said cant even be considered racists, even when taken out of context.
And another clear cut example of this, is people saying he incited violence because he told his supporters to 'punch protestors in the face', and yet his full quote is, 'if you see someone looking liek they are about to assault me, you punch that protestor in the face' But obviously they never play the first sentence, because then it wouldn't be bad