One thing the survey does not take into consideration is the actual proximity to the foreign neighbour. Just an observation, but the places that ranked 'most intolerant' are also some of the most densely populated countries, places where there will be many more interactions with the foreign neighbour. I'm speaking generally here, but in the US or Canada there is much more space and greater distances between accommodations; you do not really have to interact with your neighbour, unless you want to. Whereas even in Hong Kong, most people have to live in very close-quarters, and being someone's neighbour means seeing them everyday, hearing their chatter and noise , and more often than not, smelling what they are having for dinner.
I'm not at all denying the xenophobic attitudes of HKers, but I also wonder how people from the "most tolerant" countries would fare if they had to live much closer to their neighbours and consequently had to deal with more frequent and unavoidable interactions with them.
As Robert Frost once said: "Good fences make good neighbours".