I am aware that the RFF category is solely for an aircraft accident/incident, and that is their primary duty. At airports I have worked at they will hand over a terminal incident to the 'civilians' as soon as possible, so they can return to their primary duties, and not affect the RFF category. At the bigger airports a terminal fire may not reduce the RFF cat, however at the smaller airfields a terminal incident may well reduce or eliminate the fire cover available, if the local civilians are on strike. If they have an aircraft and terminal incident simultaneously it will be a difficult call to make.
And yes aj we're broadly in agreement, I do realise copy space is limited, and that some of our tech stuff would make dull copy too!