I notice WoB deltas with body orientation only on exhalation, not on inhalation, so long as the diaphragm is in the same position relative to the mouthpiece. I dive Poseidons so it doesn't matter at all my trim in the water, only if I am leaning left or right. With hose coming from the right, it is easier to inhale when I roll to the left because diaphragm is lower than the mouthpiece, and harder when I roll to the right, same conclusion Halocline has come to.
The chart is right when it comes to double hoses in relation to lung position only because it conveniently coincides with mouthpiece position. The mouthpiece position relative to the diaphragm is what matters most, but in a double hose the lung position is critical because similar to a CCR you are breathing against ambient pressure air through the loop hoses. Not the case in a single hose regulator.
What the others are saying can easily be disproved with a double hose. Measure WoB in the water with the double hose, then flip the tank over 180* and measure it again. Total WoB will be higher when the regulator is upside-down.