The right to fuel your own airplane with fuel you brought in from
elsewhere may also be covered by "common law". After all, it is your
property and your airplane. So long as you are not unsafe, it is your
right. Such a law would be akin to a company requiring you to fuel up
your car at the company pumps or you couldn't live in the company
housing or work at the company. Or being required to buy a Chevy if you
worked at Cheverolet. Such laws are not legal.