Back then it wasn't likely. Today? If the NSA has secure rooms for viewing confidential documents that can not leave the room? It seems pretty darn likely it is a faraday cage. You think they don't know what they're doing? Or don't have the money in their budget?
In this scenario, leaving with or otherwise distributing a copy of the document would be equivalent to walking out the door with the original. Do you really think the NSA wouldn't be able to prevent that from happening?
I didn't think the NSA would be hopelessly humiliated by a lone syadmin currently residing in Russia to protect himself from a lack of due process, but here we are.
Snowden was considered an insider. Here a person considered an outsider would be in a controlled environment with the specific purpose of restricting the flow of information.