Of course it is. But I think in the United States when people say "Asian nations" it is generally thought of as being countries where people have that traditional Chinese/Japanese/Korean/Pacific Islander phenotype. If you showed people a group of faces, and said "Pick out the Asian" they will gravitate towards the Chinese national, not the guy from Bangladesh.
Not saying it is RIGHT; just what we commonly mean in conversation.
The original post that started it all was about "countries in Asia."
In Asia would refer to a geographical place, no?