It doesn't what, read the pressure in the tire? He said the valve closed as soon as you stopped pumping, therefore you couldn't get a reading until you applied pressure to open the valve.
As to your other point, I don't know how much difference there would be, maybe very little but I would have to assume at least a little higher in the tire/tube to force the valve closed. This is assuming you subscribe to the theory that the pump head does not depress the valve. If you've ever heard a lot of air escaping as you have a tough time removing the pump head then you know the valve is being depressed, at least in that instance.

As with the original question, all of this is actually moot.