added there was no danger at any time to the passengers, crew or aircraft.
So why spend ages looking and searching?
Oh please. There was no danger because
as it turned out, there was no bomb. Had there been a bomb, there would have been danger. The security people didn't know that at the time.
Of slightly more interest, not that we'll find out, is what the "note" contained. If it said "there is a bomb on board this aircraft" then I'm afraid that the police have to take that at face value. If it was a Tesco's shopping list in Tamil which someone took for an Al-Qaeda suicide checklist because it "looks all Middle Eastern" (something similar happened in the US a while after 9/11), then it might be considered an overreaction.