Norwegian should issue advance approval without any problem. Especially since UN regulations
for "life saving equipment" and IATU regulations
both mandate that the air carriers allow these things to be carried in the cabin
, where the passenger can actually use them if the aircraft is forced down at sea. That's the purpose for the regulation.
The flight crew also have the option to "gate check" almost anything that the passenger asks, i.e. anything that is not unreasonable but for some reason, someone doesn't want the passenger to have access and control over during the flight. In that case, someone escorts "it" and the passenger out to the aircraft, and asks a member
of the flight crew to stow/babysit it until they have landed.
Something largely forgotten in the post-9/11 haste for dog and pony shows.
And in the US? Even though the TSA expressly allows gas inflators, and the UN and IATU expressly require them to be carried, note that ANY TSA agent has the authority to confiscate any item they deem a threat. And no supervisor ever overrules that decision, as a matter of policy. No matter how wrong it is.
"Then you may need to shut down flight operations. I have reason to believe there are several hundred of these already on board a number of the aircraft at these gates."
Well, if it is a security
risk, it is only fair to let them know about these things, right?