It is. However, Guk jokingly called himself that, Gene wore his like a "badge of honor", and Guczwa was a lily-white caucasion from Eastern Europe. Context is important.
Here, on the other hand, "Paki" doesn't mean anything AFAIK. Americans tend to lump all Arabs, Persians, Armenians, Turks, Afghans, etc etc under the catch-all "rag head" or "towel head". Most Americans aren't even aware there's a difference.