Not that I am seriously thinking of doing this, but just to know what happens. Suppose that I disputed the $625 CC charge as "services not delivered". Would UA go after my MP account for doing that? Or the passenger's?
I assume they’d turn around and point to the T&C that you accepted as part of the purchase. Otherwise, there’d be no such thing a nonrefundable ticket, because you could just dispute any flights that you elected not to take.