Maybe they want to live their own lives.
It says pretty clearly on the press release that it comes with a lease (therefore, he does not own the property):
"...a terrific landlord, a very fair monthly rent of under $15,000.00 which includes all common area maintenance…"
I'm curious why his kids seem to want nothing to do with this business. They've always been front and center at the US Open. If it is so profitable and valuable, wouldn't they want a piece of it?