Wow! That certainly sounds like bad customer service, unless there's something deeper that we don't know about.
Mac's does not own Bry's or the ramp. Mac's is used by Bry's to allow people to purchase access to the ramp as Bry's is not as local as Mac's (and Bry's does not open as early as the ramp user would need). Therefore, Mac's does not care about the ramp business. He probably does not make a bunch of money off the key rental.
That being said, Mac's does not have the greatest disposition when it come to his customers. He treats people like they are a bother to him that they came in. I don't know how he could have stayed in business for as long as he has. I guess it's location, location, location.
It certainly isn't his business attitude that keeps them coming back.
The new owners of AP Marina (now named Seaport Inlet Marina) also now have a stake in the docks in the north channel. I don't know if that ownership includes ramp or not.