Fuel on board is and always has been purely for awareness of endurance. - you gonna start quoting figures for the Environmental Protection people and newt-counters too? Just get on with your own job and let others do theirs.
POB is a figure that every prudent airman writtes in bold on the top of his PLOG, doesn't he? It is the whole point of a headcount before departure and is a whole number, never ever "plus" or "minus" anything. Just a number to which he has already added the crew. So he doesn't have to add up when it all goes to cactus.
Airmanship, it's called.