This property does not offer complimentary airport parking, so I see no reason people not staying there would scam a free ride on their shuttle bus. Regardless, the shuttle bus driver checks names against a list of guests with reservations. If you don't have one, be prepared to deal with it

Frankly, if you arrive at the commuter terminal, and the shuttle bus is not already at the terminal, walking to the hotel is quicker. From the main terminals, walking is marginal vs waiting for shuttle bus. Without luggage and with good weather, I would walk from either terminal is the shuttle bus were not already waiting.