The only cause that is being promoted is that it may have been caused by the restoration which was in its early stage.
It would seem that a responsible restoration would have a crew assigned to check that nothing potentially flame-causing was left out and around after the work crews finished for the day. Also, it would seem that you would avoid having moozlum workers. Just sayin’. If, indeed, it is moozlum arson, the government there would never say so.