His logic is correct though. The native power of his grid is 12V. He has a 20V step-up circuit and an inverter. 12V -> Inverter -> 12V is only good for UPS. He can directly setup USB-PD up to 9V from the 12V circuit or full 12V PD from the 20V one.

Also, I believe he hoards the power bricks as he notes.

What he does is not ideal, and I don't share the same view with him, but I understand what he does.