I think the thing with the people who keep bringing this up is that, yes there are some Asians who don't have this Asian gene variation. Just like non-Asians, they will have really bad BO, and since deodorant isn't really available, they get used to it and don't think there's a problem.
And it really only takes a few of these people to stink up the entire train.
That is supported by the article and isn't evidence to the contrary. The 80-95% off people who don't smell bad on the train are automatically discounted because there are people who do.
I think I have a new theory.
80-90% of East Asians don't emit BO due to the lack of this particular gene. Deodorant isn't commonly sold or used as a cultural norm as a result in East Asian countries, because the market isn't there for it.
That leaves 10-20% of East Asians who DO have this gene and do emit BO. Problem is, since deodorant isn't a culturally normal thing to use and is difficult to find in stores, they don't end up using it. Therefore, that 10-20% of the population end up stinking up the trains and workplaces.
This causes confusion about whether East Asians smell as much as everybody else or not, because 10-20% of East Asians who do have the smelly gene is still millions of people.
Aka. confirmation bias. You notice the smelly ones but you don't notice the non-smelly ones (most of whom don't actually use deodorant and don't smell anyway).