"No Indians, No PRC" can also mean bias on citizenship (i.e. politics)! That might be especially so when the same (Han ethnic) Chinese from HK or ROC would meet no hardship. So it may not necessarily be the race (or at least not for all landlords) as it may be the way they expect that their tenants will think or behave. It's called Memetics, and until naturalization in a new medium the individuals may present a higher risk of getting themselves at odds with the others around them.