I am wondering too, if LHR should have been shut for so long. I understand the immediate concerns of supervisors dealing directly with incident(s) but what about the wider operational issues? Are decision makers aware of many operators fuel policy, such as dispensing with alternates? If any diversions involved Pan/Mayday calls, it means that the closure decision generated emergencies in its own right. To have large numbers of aircraft with low fuel states diverting is a serious matter in itself.
There is a legally defined number of fire and other emergency vehicles that are required to be available for operation of Heathrow. Obviously, they have only enough to deal with one incident, in this case a localized fire on an empty aircraft, or they would have continued flying. This is a cause for concern as there is an obvious possibility (probability) that two incidents could occur at the same time or there could be a really major accident- and Heathrow is demonstrably unable to cope.