I was not aware that the error bars between kashrut and marit ayin are that wide. I figured that it was because of the intersection of Jewish middle class culture and Chinese culture starting in the 1930s, and because Chinese restaurants generally do not serve dairy products.
This is all apocrypha, so take it with a grain of salt. But my understanding is that this would be a case where marit ayin would not be a significant concern, since the Chinese dishes in question were not visually identifiable as e.g. pork.
Or another framing: if you were a semi-secular family (like mine) that tried to keep a semi-kosher home, it would be easier to eat a dish that contained finely minced pork or shellfish or similar. American Chinese food fits those parameters while also being available on Christmas, etc.
