SHT may have been unwilling to declare an emergency because there was unlikely to be one.
EGGP may have been closed, but if that was known to the SHT crew prior to departure then they would defintely had fuel for another alternate. If it was an unforeseen closure then if ATC delays were expected to mean that SHT landed with less than final reserve fuel, an emergency call is necessary before ATC can take any 'expediting' action. It certainly doesn't mean that aircraft are running on fumes or likely to fall out of the sky.
Whilst there is no such thing as a 'fuel priority' call in UK airspace, the SHT crew were showing good airmanship by being open with ATC about their situation, allowing ATC to offer some flexibility if available, or if not, to advise the crew ahead of the game.
Fuel loading is always at the ultimate discretion of the PIC, but pilots do make such decisions with reference to commercial considerations as well as purely operational ones.
Excessive fuel carried not only wastes fuel by unnecssarily increasing aircraft weight, but causes extra wear on brakes, flaps, structural components etc.
Were you listening to this on an airband radio, by any chance? What would you have done differently?
The scenario certainly doesn't seem like poor form to me, and ATC workload in the event of a diversion ought to have in fact been much less in this case, had it proved necessary, since the crew had the airmanship to give them advance warning of the situation.
What is your experience of ATC workload levels in various scenarios from inside an ATC Centre? What makes you think that a div would have degraded safetyin this instance? How are you qualified to cast aspersions on the 'form' of the crew? Not necessarily sarcasm, just that more info on the context of your concern would be useful in answering your questions more fully.