I think it's a lovely photo, she looks a little tired but very content. It's clear she has a boob out, but you just because you can't see a nipple in a mouth doesn't mean she isn't, or hasn't just been, nursing.
As for being out on the town within weeks of giving birth, well, I know two or three mums who have been in the pub two weeks post birth, leaving new-borns with grannies etc. And some of them were bf, and had been pumping to leave enough boob-juice for junior to have over night. I wouldn't do it myself, but Brangelina are notorious for taking thier tribe with them everywhere, and who is to say they stay out all night? Perhaps they get snapped on the red carpet, watch the premiere and then sneak out the back and go back to the kids, which would mean they were away from the babies for only two or three hours, so is do-able, even if you have huge leaky boobs!!
As far as I'm concerned it's a very beautiful picture, and if it helps to make breastfeeding more normal then I am very pleased they have released them to the public (I'm sure they donate most of the revenue generated by these kind of pictures to charity too). And of course she's showing J-Lo how it's done......so thats super-cool by me!