Gary Coffman writes:

The regulator isn't a resistance ...

What nonsense. It's as much a resistance as you pinching an air hose,
or you partly opening or closing an ordinary manual valve in the line.
The only difference in a regulator is that the opening and closing is
controlled by the downstream conditions, instead of your hand. If your
hand is quick enough, you can read a gage and do *exactly* what a
regulator does.

Air and its associated energy not needed to meet the demand simply
remains upstream of the regulator, normally in a tank, but in your
Sea God case, in his lungs. It is emphatically *not* dissipated in the
regulator.

More nonsense. Only the mass is conserved to remain upstream. The
pressure of the mass of air passing through the regulator drops (the
nature of a regulator, after all), and thus the regulator introduces a
waste of some of the energy available for work at the input condition
versus the output, whether or not you care to label this loss
"dissipation", whether or not the end result is heat or not, whether or
not the regulator itself gets hotter or colder.

It is stupid to believe a restriction (dynamically controlled or not)
transforms pressure and volume from input to output with no significant
loss of work potential.