After they saw she didn't have a bomb, they should have let her off. Instead they charged her with "possessing a hoax device" and threatened anyone else wearing exposed circuitry with potentially being shot.
OK. Yeah, that is where it gets arguable and gets into the realm of where lawyers and judges come into place. I don't think the Police's decision making process as far as charging is concerned is relevant here. I think if she was actually fined, it means that the law is broken and that is something the legislation should change on.
As far as the whole "potentially being shot." thing. I am unclear of what to say there. They are investigating a potential threat, if it was indeed a threat. The guns are necessary there. I am not clear how wearing an exposed circuit board connected to a 9Volt battery with what looks like putty is different from me waving a toy gun around in a bank. Should that imply that if someone had something that looked like a weapon, the cops shouldn't draw their guns? Sure, I don't disagree with the statement that not all bombs are open circuit boards. Neither are all open circuit boards bombs. How do you however practically implement an alternative solution in such a scenario? Complaining about the cops is useless unless you are bringing up a solid alternative.
Circuit boards and putty are not weapons. Are you aware of any instance where circuit boards and putty were used to harm someone? Are such events a big enough problem to justify threatening law-abiding citizens with machine guns?
There is no factual basis for linking her activities to a bomb threat. Bombs do not look like that. Perhaps a bomb could look like that, but a bomb can look like anything, like a rolling suitcase.
My solution is to allow cops to step in only if they have reasonable suspicion to believe a criminal act is taking place. An unrecognized object should not be considered a weapon unless it is being used in a threatening manner. Walking around an airport should not be considered threatening behavior.