"How are you going to get hacked if I talk about your mainframe? It's not connected to the public internet, is it?"
"No. Well... we don't know... but ... hackers! Hackers are really smart Marianne."
Part of the compromise was that I promised I would only use information that was already available publicly through government reports and news articles. I went back through my talk and documented where each fact was already published somewhere else until they were comfortable with it. So the ambiguity on whether the 7074 was the actual machine or an emulator was deliberate... there were certain things I could not find a public comment on and therefore agreed to avoid making direct statements about.
This all seems super annoying, but it makes sense when you realize how heavily scrutinized public servants are. In the end they are only trying to protect me, my organization and Obama's legacy. Three things that are really important to me. So I can't exactly blame them for it. I was happy to be able to find a middle ground where they felt comfortable, the organizers weren't too badly inconvenienced and I got to give the talk I wanted to.