I tried to use the GC entrance a few weeks ago around 8:45 in the morning, as I was running late for a reservation at Ariel's Grotto. The CM at the gate asked for my room key, and would NOT let me through.
Last week, I was there with hubby and we used it to go from Rainforest Cafe to DCA after lunch. The "hotel guests only" sign was gone and the CM DID let us through...I asked why it was OK this time, and was specifically told because it was after 11am.