For some reason these things come down to the "bad seed" ("ethical deficit") argument (don't we all have an ethical deficit?). I'd argue that Trump is playing on ignorance, feelings of betrayal, and nationalism, but not that his supporters are as a group have an ethical deficit. 
I'd agree the implication is that the vast majority of immigrants (in Trump's statement) are bad people by the way he says some are good. And you are correct:Stats show they commit fewer crimes residents. But I think Dale is hearing that Mexican criminals and illegals (their term) need to be kept out. 
Now, Trump may be insinuating that Mexicans in general are criminals, but an insinuation is more subjective than a direct statement "Mexicans are criminals". If you want to see a good treatment of this, try :http://www.salon.com/2015/12/21/the_media_needs_to_stop_telling_this_lie_about_donald_trump_im_a_sanders_supporter_and_value_honesty/
Lastly, who does the "entrusting" other than people?