I think you might be missing the point. DannyBee says that requesting documents from Facebook in the UK would have been a fine option. But that's not what happ

I think you might be missing the point. DannyBee says that requesting documents from Facebook in the UK would have been a fine option. But that's not what happened here! The documents were obtained from someone who was essentially a third party, that just happened to have access to them. Facebook was not willingly doing business with this person.