Assuming this is not a total media beat up and on the basis of the information provided, as a humble passenger, If I find out that a bomb threat has been made and you do not evacuate me immediately on the ground, then I'm either going to evacuate myself or sue you for every last dollar for needlessly exposing me harm, imaginary or not.
There is a law enforcement doctrine that treats the possession of a replica weapon exactly the same as a real weapon. I suspect that this principle would be easily extended by the Courts to apply to "replica" or imaginary bombs.
For example, if someone threatens you with what appears to be a firearm, you are entilted to believe it is real and act accordingly, including killing the person holding it, without any further action to ascertain if the threat is real or imaginary. The fact that the weapon is a "replica" or "Toy" is regarded as irrelevent. If you would like to test this hypothesis, try taking a plastic toy gun through screening and see what happens to you.
No one looks at a replica and gives it a "figure of merit" as to its accuracy of depiction. The idea that you can give a "figure of merit" to a bomb threat and safely ignore some of them is therefore patently absurd. The pilot would be quite within his rights to order an emergency evacuation.
Translation: No one is entitled to expose myself or anyone else to the slightest risk without my express permission and certainly not to "smoke out" a culprit as part of a law enforcement activity.