Alas, I don't know about Mormons in Germany, but I can ask my colleagues here in Stuttgart (I'm Hungarian and a workaholic, so my 1st hand knowledge of things here is not so good). My impressions about Germans and Turkish guest workers are mixed: I think they don't like them, but on the other hand Turks are becoming better and better integrated, and they are just part of the landscape, period. Germany's favourite fast food joints are all Turkish, for instance. (And they are remarkably secular, they serve alcohol, e.g.)

There is at least one Turkish TV-station, and everywhere you go you see Turkish signs and inscriptions, too.

Even relatively conservative Stuttgart, btw, is incredibly mixed ethnically: Russians and other Slavs, Albanians, Chinese and Koreans, you name it. I think there is also a considerable US presence (with banks, corporations). "Real"  Germans here are slow in accepting for'ners (including Germans from elsewhere), but things improve with time.

Back to your initial observation: it's intriguing that Mormons should seek to discreetly stir up things.
Why would they do that? But I think the presence of immigrants is just a given -- and quite a few Germans can see the benefits of immigration, if only in the form of nice food.

A dog's a dog. A Cat's a Cat. (T.S. Eliot)