we will all be angry if it does turn out to be a bomb.
That might be the case but it will be of more concern if this was a structural failure.
To some extent we can take precautions against outsiders taking action even though these actions may only be to reassure passengers and to make it more difficult for the perpetrators. Structure failures would reflect on the airworthiness of a lot of aircraft currently in service with far more repercussions.
FF