You don't see how this is illogical? Relocating a population isn't going to magically make it perfect, nor should it magnify the inevitable incidence of criminality through some moralistic white savior lens. Even if you were taking in the most highly affluent and educated group, and even if you were setting aside problems with culture, with logistical difficulties, and with subsequent poverty and lack of economic viability, the laws of nature would still yield that some would engage in criminal behavior by a matter of numbers. Do you then think, for instance, that America turning away Holocaust refugee Jews was okay because it wasn't realistic to expect that, of the millions in need of a home, none would engage in criminal behavior?
I mean....you see why that paternalistic indignation is inherently very shitty and stupid, right? It feeds in to a line of thinking that not only unfairly prejudges along ethnic and racial lines, but in fact makes any sort of humanitarian policy unfeasible.
As far as the rest of your post, it just seemed to me to be anecdotes that I cannot verify, but which certainly don't match up with my own experiences with Middle Eastern and North African migrants, and conjecture on how we should ignore the plights of fellow humans for fear of the reaction of our own moronic countrymen. That's shifting the blame from one group, which is completely worthy of criticism on the matter, to another who are completely unrelated to it. If right-wing nationalism begins to rear its head, it's not up to us to scapegoat and expel helpless people: it's up to us to introduce the nationalists' heads to the pavement ourselves.