I replied to shaitland with a more detailed response. Both of you are hitting on the same question which is air travel should be a fundamental right and if it were wouldn't that negate the consent issue? And the answer is almost certainly. The problem is that it hasn't been held to be fundamental. I think I made a strong constitutional argument for why it should be, but the Supreme Court has not held that and may never. Therefore the consent issues still hold until that happens.
Concerning your statement that I somehow believe that murder or stabbing a person is a consentable act, I don't know where you get that.
First, I'm not sure what you're even getting at. I can see three different readings. First, that a person cannot consent to be killed. Second, that a person cannot consent to be murdered. Third, that a person cannot consent to be killed/murdered by a TSA agent or other government actor.
First, a person can consent to be killed it's called physician assisted suicide. Some states, I believe Oregon is one, do have this law.
Second, you cannot consent to be murdered. This also covers consent to be killed by a non physician. Here's the problem with your example: there is no consent element in a murder charge. The prosecutor doesn't have to prove that the victim didn't consent. The defendant could claim that the victim consented in some way and try to get the charge reduced from murder to manslaughter, but that's a mitigation defense aimed at the jury not a question of law. In practical terms, that means you would file a motion for summary judgment with an affirmative defense of consent. The court will just throw it out, but feel free to tell the jury that. But, the court would never consider this so there really isn't any Fourth Amendment implication. Further, private citizens are not bound by the Fourth Amendment and so cannot violate your rights. That means consent doctrine with a private citizen is inapplicable. Feel free to break down your neighbors door and take pictures of all his illegal activities. You'll be charged with trespassing and other charges but the police will be able to use whatever you find even sans warrant.
Third, if a government actor, TSA agent, officer, FBI, DEA, stabs you for no reason then they are acting outside of their authority and are considered a normal citizen. Again, can't consent to murder so still not an issue, and the private citizen cannot violate your Fourth Amendment rights so there is obviously no need for consent.
The basic premise of your analogy is flawed. You can consent to waive your Fourth Amendment rights but cannot consent to murder. Your premise would be correct if TSA searches were illegal, but that's the problem I talked about in my first post. You'd have to distinguish TSA searches from all others just like it. I don't see how you can do that so your consent to a crime analogy is out. However, if it were held that TSA searches are criminal then it's in, but then we wouldn't be having this conversation.
In summation, you can either get the Supreme Court to elevate air travel to fundamental right status or show that TSA searches are all illegal. Either way and your aces. Problem is TSA searches have constitutional parallels you'd have to navigate while the fundamental right path builds off the Supreme Court's own rulings. I'd go fundamental right which would solve all these problems, and you wouldn't have to explain how TSA searches are different than every other governmental agency search.