My understanding is that #1 is correct, but #2 is not - it’s either open or closed.
I haven’t used it yet, but a friend parked at TS last week and said security in the lot was not available, so it worked like it always has for her. Her impression based on how the area was set up was that it’s open in-lot and you use it, or it’s closed and you don’t. Since the busses would let off into a secure area, I don’t see how they could allow guests not to screen in the lot? Seems like a logistical issue to have different busses for screened vs unscreened guests?