Dargay and Gately base their logic ...
Ms. Heaven (the author) needs to look-up the word "logic" in a dictionary.
...the demand for oil no longer appears to respond to price.
Well boil my buttons. I don't want to be some kind of pinko-commie DFH but doesn't that imply Demand Inelasticity?
(A situation, we are assured by NCE, is Unpossible.)