I think many, including myself, have always had "some" doubts about "some" of these sales but maybe that's just driven by envy.
I haven't taken the time to check what happened with all the other big recent sales but the fact this one points to the .com certainly seems to legitimizes this sale... although it's not exactly clear why that particular company would care so much about an .xyz domain. They probably have money to burn and the price may have been peanuts for them to protect their brand, like @silentg said. I'm guessing companies also paid big bucks for other random extensions, like .biz and whatever, once upon a time.... but not so much anymore...?