Well, I would hope you could get out without a key, otherwise, it would be the Graybar Hotel.
Anyway, I never said you can't go OUT through the gate, simply said that you can't
enter Grand Californian as a pedestrian without having a room key, meaning neither entry to DCA is accessible from
Disneyland Drive (the front entrance to the hotel). If you're standing out on Disneyland Drive (say, as a guest at the Westin), the only way into DCA is through Downtown Disney to the Esplanade, or Downtown Disney then through the Grand Cal lobby. You can definitely walk out to go to Great Maple, but if you don't have a room key, you'll need to have someone open the gate for you to get back in to Grand Cal.
The post I was responding to read:
And I was simply adding that for anyone trying to walk in off the street, you need a key to get IN through both pedestrian gates (the
Pixar Place DCA gate, as well as the sidewalk gate into Grand Cal).