As always, you make insightful and valid points. A pleasure to hear from you again!
I see two major points in your response — that the historical examples I utilized may not prove the point, and that rural society may actually be more receptive to new ideas/cultures than urban societies. I’ll address them in turn.
For the first, I still stand by my examples as relatively multicultural. As you wisely note, that does not mean that all factions within Rome, Athens, or the early caliphates were supportive of multiculturalism. Nor does it mean that they were particularly tolerant by today’s standards (their intense limitations on citizenship, for example). But based on my limited knowledge, they were more tolerant of the multiple cultures existing within their boundaries than the counterexamples we refer to. However experienced the Crusaders may have become, their goal was to kill Muslims and establish a uni-cultural Germanic kingdom in Palestine. And the Mongol Yuan Dynasty and the Middle Eastern Ilkhanate both lasted about 100 years each, and within that time managed to alienate significant portions of their populations (contributing to their demise). So it seems reasonable to use Greece and Rome as examples of more tolerant societies, given the times they operated in.
As to the idea that rural societies are more receptive to new ideas and cultures than urban, I’m skeptical. You present some excellent counterexamples, and my examples were just anecdotal, but the argument seems intuitively unlikely. The culture of the Roman Empire was dependent on Rome, however intolerant Rome may have been sometimes, so any multiculturalism in the Empire likely originated to some degree in the city. And while New York and Philadelphia may have had more Loyalists than the Southern colonies, I am under the impression that it is only because they had more people — Loyalist fighters won most of their victories in the Southern colonies, if I remember correctly. Still, it is certainly possible that rural communities are more receptive at times (e.g. the Chinese Diaspora); I’m just willing to bet that it’s more common that cities accept the outcasts and renegades.