I should maybe have pointed out in my post that I'm a woman, and a mother of two.
I live in a city where you even at some public coffee shops get a free cake for breastfeeding, but still understand that this is not the case in the rest of the world and some might find it uncomfortable to witness someone pumping if they didn't cover themselves. Again, I'm sure she would have preferred to do it elsewhere (not the lavatory) and I don't see any mentioning of her not trying to cover up, as it was the sound that was the complaint here, not whether he saw or not saw her breast.

I am sorry the OP didn't get any sleep, but there are a hundred other reasons why his sleep could have been interrupted (it's a flight and a public place) so my sympathies also lies with the woman here. And as already mentioned, a lavatory is not a proper place for pumping, as it is not especially hygienic and it would block the access to the lavatory for quite an amount of time.