"The constitutionality of an airport screening search, however, does not depend on consent, see Biswell, 406 U.S. at 315, 92 S.Ct. 1593, and requiring that a potential passenger be allowed to revoke consent to an ongoing airport security search makes little sense in a post-9/11 world.6 Such a rule would afford terrorists 7 multiple opportunities to attempt to penetrate airport security by “electing not to fly” on the cusp of detection until a vulnerable portal is found. This rule would also allow terrorists a low-cost method of detecting systematic vulnerabilities in airport security, knowledge that could be extremely valuable in planning future attacks
. Likewise, given that consent is not required, it makes little sense to predicate the reasonableness of an administrative airport screening search on an irrevocable implied consent theory. Rather, where an airport screening search is otherwise reasonable and conducted pursuant to statutory authority, 49 U.S.C. § 44901, all that is required is the passenger's election to attempt entry into the secured area 8
of an airport."