Oh dear it appeared hopeful at one stage this morning but the ill & uninformed posted as feared.
I honestly began to think that the question..."why did a bus on fire necessitate closing/evacuating the whole airport?"... would not appear on a "professional" forum.
A little thought,common sense & knowledge of the situation that evolved quickly coupled with familiarity of the layout at STN would save the "clever" remarks.
Kudos to the terminal management who took the right decision being fully aware of the disruptive ramifications for ops later to evacuate thousands of pax to "safety" airside.
Perhaps the speculators here would have preferred to be evacuated outside into acrid smoke & an unknown potential threat anywhere landside.
The first duty of the terminal management is toward the travelling public & staff`s safety & in this they fully succeeded.