I have the same question. I thought "những" denoted plurals? It's accepted with "những" going from English to Vietnamese. There are a lot of confusing inconsistencies in these lessons; I'm figuring them out, but it might be better to try and make everything consistent before this comes out of beta.
'he doesn't need woman'is not a valid english phrase. If he can manage without any woman then the choices are; he doesn't need a woman or he doesn't need women. If you want to say he doesn't need more than one, you would do it by stressing the word 'women' in speech or adding a phrase like 'more than one' if you're writing.