Blind faith in anything is the path to destruction.
My distinction is this, if we view it so broadly as to include everyone on "this aircraft called the USA," what, then, could possibly be an unreasonable search or invasion of privacy?
Government isn't getting smaller. No matter who's president, our tradtional rights as US citizens are our only protections and they make this country the envy of the world. Sure, this president has good intentions. Will the next, when our traditional rights are long gone? This used to be a concern of Conservatives.
We took what many would claim to be "drastic" measures during all our wars that intruded on personal privacy. And yet, here we are, still the freest nation in the world. Your slippery slope argument is, thus, shot down.