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)
This was posted as an opposite to what OP posted, to point out his sided point of view while fortifying his opinion with pretty much unrelated, emotional part of history.
I made sarcasm very obvious, especially with exactly saying it was that, in the second line.
Learn how to read in between lines.
Edited the post so no one else thinks it is the real reply.
When talking about potentially inflammatory topics on the web, expecting the reader to "read between the lines" as you say is probably never a workable idea as there can be and are enough potential speakers across the entire spectrum of opinion that any intended meaning could be possible and potentially valid for "reading between the lines" (hence Poe's Law[0] and other challenges in the discussion of complex topics on the web when the range of speaker opinions and audience opinions is large and unknown).
No one ever expects Poe's law to apply to their own sarcasm, but unfortunately it always does.