Cockney Steve
I think you misunderstand the proponents arguments, so let me try to explain (but note I am not taking sides.)
An aircraft can depart legally if it is within its weight parameters, so long as it is not above the MTOW (maximum take off weight.) However, it must also plan to arrive within its maximum landing weight.
So the aircraft may be okay to take off, but not to land and the captain cannot depart under those circumstances (see Hunter 58's post.)
The other argument is whether the aircraft sitting with excess fuel is a technical or non technical matter.
Safety Concerns says it is non technical, as it does not require an engineer to deal with defueling and quotes IATA message codes to support his view.
Beazelbub says (as an airline captain) that an overfueled aircraft is a technical matter.
Hope this clarifies the argument for you
