"Iacuzza's car was inspected by valet attendants on orders from the TSA."
United States v. Jacobsen, 466 U.S. 109 (1984): "This Court has ... consistently construed this protection as proscribing only governmental action; it is wholly inapplicable to a search or seizure, even an unreasonable one, effected by a private individual not acting as an agent of the Government or with the participation or knowledge of any governmental official.".
Wouldn't the 4th still apply since the valet attendants are acting on the direction of government agents?
The flip side of the argument is that the vehicle's owner has already consented to provide access to the valet driver - and it's the valet driver that has abused that consent.
Pretty sure the police (for example) can't just stop cars and search them without probable cause, but the standard for vehicles is lower.