I've never heard of anything other than an actual weapon, or something that can be used as a weapon, be "confiscated" by airport security.
If you take it as carry on, they certainly may open your bag and inpect it but they can tell the difference between a bomb and a light. The worst they will do is check it as baggage and not allow you to take it onboard the passenger section of the plane with you.
If you just leave it on your bike and check it that way, they may open your bike box to inspect things but they will not confiscate anything that is not actually dangerous.
Also, TSA's policies are changing on a nearly daily basis, there are certain items that they allow onboard today and not tomorrow and then they allow them again on the next day...There is no way to know what to expect, it is set up that way on purpose as a security measure.
Adventure Cycling Association