[tptacek]

That's not the doctrine the searches fall under.

[mikeash]

So then what does it mean that "you consent to the search by choosing to travel by air in the United States"?

[tptacek]

Exactly that? Consent isn't what enables the search, but it's still good that the TSA can't raid your house. What enables the search is (i) no investigative intent and (ii) no discretion on the part of the searchers as to who to search.