Just to repeat, it was not ISU or the French federation who decided to cancel but government officials (not sure if national or specific to Bordeoux). I'm sure that the continuing investigations on the terror attacks and the risks of holding an international competition were deciding factors. It just emerged that one (or more) of the attackers had tickets to the football match but were stopped at the gate when they were searched and found to have bomb vests. They detonated it instead outside of the stadium injuring and killing people. Imagine how much more if they made it inside the stadium? This happened just the night before and was a well organized terror attack. What makes you sure that there were no plans to do this at other international events, with TEB being one of them? What makes you so sure that there are no lone wolf terrorists who won't be inspired by these events and decide to go over to TEB?
People talk about not allowing spectators but there are more involved in these events than just athletes, their entourage, judges, and skating representatives. How about the support staff needed for such an event? Have they been properly vetted? Can TEB organizers assure in less than 24 hours that they have made sure those who have access inside are all above board and that no one else can have entry?
There are raids in possible terror cells in Belgium, who knows if police in Bordeaux are also actively trying to investigate to make sure there isn't a threat locally.