Wow. The translation of your "How do you know that such an imigrant is not being a criminal?" to the equivalent statement in 1930's Germany is so direct and so poignant, I would have thought you were trying to support the parent's post, but I believe you're using that line to try to fault their thinking (which I find genuinely frightening in terms of the object lesson it presents on the ease of vilifying a "them" group, and how easily that kind of rhetoric can creep into polite conversation)