[T.Smith]

Question: If during the course of one of these searches they were to find something illegal but not related to terrorism, could they arrest you? For example, if they find a bag of weed or a pirated copy of "The Reagans", could they arrest you?

I think doing so severely violates the prohibition against illegal search and seizure. That is, if the initial search didn't already.

[Viva Le Dissention]

Oh, I'm sure they would arrest you.

It's not like they'll catch some drug smuggler and then say, "Well, have a nice day! And, um, would you mind not smuggling those drugs, please? That'd be great. Thanks."

[webstersII]

Check out this thread about Montel Williams. I think it answers your question.
http://www.freerepublic.com/focus/news/1052587/posts?page=1

[Sender]

Question: If during the course of one of these searches they were to find something illegal but not related to terrorism, could they arrest you?

They would probably say that by driving into an airport during known code orange conditions, you have waived any expectation of privacy, and God help you if you have anything illegal in there.