Well here is the more applicable quote from Sheldon Brown;
"Rolling resistance" is the mechanical friction generated as the tire rolls. As a segment of the tire tread rolls into contact with the road, it deforms from its normal curved shape into a flat shape against the road, then back to the curve as the tire rolls onward. The deformation of the rubber in this process is what causes the friction.
There are two ways to reduce this friction, each subject to trade-offs:
The thinner and softer the rubber/fabric of the tire are, the more flexible they become.
The trade-off with this is that the thinner the tire gets, the more fragile it is, and the sooner it will wear out.
The higher the air pressure, the less the tire will deflect.
The trade-off with this is that if you pump the tire up too hard, you lose the benefits of pneumatic tires: the ride becomes excessively harsh, and traction will be reduced. In addition, extremely high pressures require a stronger (heavier) fabric and stronger (heavier) rim flanges.
Rolling resistance does decrease theoretically with any increase in pressure, but with modern, high-quality tires the rolling resistance at correct inflation pressure is already so low that the infinitesimal reductions gained are more than outweighed by the trade-offs. "
I go for long term comfort on my touring bike, and not concerned with "infinitesimal reductions" in rolling resistance. My Conti's sit at 70 psi, or below if I'm too lazy to pump the tires that day.