your opinion was that :
Thus, legally, the PIC doesn’t have sole ultimate authority as far as how much fuel gets loaded—that’s a joint preflight decision between PIC and dispatcher.
However, § 121.533
The pilot in command and the aircraft dispatcher are jointly responsible for the preflight planning, delay, and dispatch release of a flight in compliance with this chapter and operations specifications
And, § 91.3
The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.
Your own evidence clearly shows that whilst the Captain and the dispatcher are jointly reponsible for the planning etc. The Captain (PIC) Does indeed have ultimate sole authority.