While everyone is keen on the 'bomb theory' - remember that security services will immediately think was it a bomb - as that is what they do. Aircraft engineers will think break up and "where is the HS?" as even if the tail breaks off the HS and VS normally stay remarkably intact.
But politicians are advised by security services so will take action against security threats as that is a threat to their jobs and they need to take action to keep votes.
So - having said that - if the HS has a problem and departs the airframe, does that cause a fire? Well we have that answer on video already from earlier in the thread where an aircraft lost its HS while flying behind a tanking F-4. Guess what the aircraft went into a severe bunt, suffered structural failure and exploded in flames while airborne, then another large explosion on the ground. So a 'heat signature' from the airborne aircraft does not mean bomb any more than it means structural failure.
There has been no bomb residue found.
The HS parted company with the empenage in a most unlikely way not seen in any other aircraft bombing.
No answers - but before we start grilling low grade catering cart operatives and blame them and lax security, it would be better to get real evidence.