If the airlines have rules that the passengers must stipulate in purchasing their tickets, enforcing those rules falls under the libertarian rubric of fraud. The fact that air traffic is partially in the public domain and therefore, partially heir to constitutional restrictions complicates this picture, so lets dig a little deeper.
Can you wear C4 in your shoes in the privacy of your own home. Sure. Can you wear C4 on an airplane full of unsuspecting passengers? Of course not, not any more than you can enter a freeway on the offramp. Putting people unduly at risk of tort harm, is tort harm, and can be enforced on that basis without demolishing the plain directions of the Constitution, thank you very much anyway. The fact that c4 could be harmful is an inadequate reason for a blanket ban on c4. What you are doing here is seeking a Consitutionally abrogating warrant because you can point to some harm. This will only work in children's fantasies. In a Constiutionally limited Republic, you have to make a case before throwing someone in jail. Does my annoyance with woman's eye make up give me a right to ban it? Some woman have been blinded by it, you know. That's harm isn't it?
Under the Miller decision, it would be if C4 were used by the infantry. (The SC ruled that sawed-off shotguns could be banned without a 2nd Amendment violation if they weren't usaed by GIs.)