> By what possible rationale could you say that recent immigration has anything to do with this
I didn't say it was recent immigration that caused this incident, we both know that (if they are 2nd generation, it couldn't be recent).
> other than that they're Muslim
You think that their religion has absolutely nothing to do with this? I mean, even unjust prejudice within their host country because of their religion could easily cause social isolation and economic disadvantage leading to anger - that seems like a perfectly reasonable explanation to me and largely places the ultimate blame on the host country.