I am wondering how much this policy relates to the overnight queue vs the day queue?
I have never done at overnight queue. Four of us lined up for the Animation session and had decent spots near the front at 11-11:30AM in Hall E on Friday. We got our wrist bands and all. No one ever said there was an issue leaving Hall E. When we asked, we were only told that if the queue started to move into the seating area and you were not back, you would lose your place. So do not cut it close on returning.
My then DS23 and DS19 left to go into the main Expo floor to see the new Star Wars Battlefront video games. They were gone for maybe an hour. Then later one of our group went off to grab some lunch for everyone and bring to back to the group as the options were limited inside Hall E. From what we saw at the 2015 Expo it was no big deal to do this as long as you came back with plenty of time.
I did not stay overnight like you did, but do seem to remember that they had a different policy for the overnighters to avoid having one person hold a spot for the others in the group who went back to their hotels to sleep. If you went in overnight you could not leave. But once the main convention opened in the morning they had a different policy. At least that is what I remember.