Yep, I suspected it..it's a turkified arab word that was hellenized;) It was integrated into Greek from Turkish, not Arab. One could say that's why the noun is "μουσαφιρλίκι", with the distinctive -lik ending.

BTW (and to return to the greek language but not in its ancient form, at least for now) such words didn't "appear" because of the adaption of demotiki, they were a result of the interaction between the various people that inhabited the same territories. Katharevousa was an artificial way of expression, people spoke their own language. The debate about it was intense during the beginnings of the 20th century, in the 1980s, it was just the reasonable thing to do.
Languages aren't constructions (well real,lively languages), they evolve through time and adapt to modern needs and forms of expression. Many a magnus opus of greek literature is written in demotiki, or demotiki with some words in katharevousa which had a special role in those texts.