I'm sure you see a lot more Chinese men than I do, so maybe there is something to what you have observed; I've never seen an instance of BEB in Chinese people, either in person or in the literature I have read. However, I am sure the shape of the eyes has nothing to do with BEB, which is caused by misfiring of the 7th cranial nerve -- completely unrelated to the racial eye shape.
I work for an international chinese company and I have seen it in 2 or 3 out of about maybe 15 chinese men that have worked here. They all come from Taiwan, so I was thinking maybe is the food, (lack of some nutrient, vitamin or mineral) or excess of.
Personally I have had it on and off since I was very young, and it comes and goes, some times more severe and some times very mild, but it aggravates under stress or when I'm the center of attention, (i.e. when I'm being filmed).
I was very nearsighted since I was about 8 or 9, and recently had laser surgery. It worked beautifully, but the spasm have not gone away. My eye doctor says everything is excellent with my eyes, that is just a tic. (since before I was 10?).he is very good and has been in charge of my eyes all my life.
Anyway, sorry for the rambling, I wanted to mention I lived in FLA for a year and when I arrived I had it, but it went away after a week and didn't return during the whole year. Maybe it was the weather change, since where I am is very humid, and there it wasn't.
Sorry this is so long, but I think this is all very curious.