[computer]

Also, consider the fact that you have to show the TSA your boarding pass. If you have to unlock your phone for that, they get full access to copy all your data if they decide you look like a terrorist.

Likely not a consideration for most people who don't mind privacy stuff, of course.

[ewang1]

Apple's Passbook works from the lock screen without having to unlock the phone itself. The pass shows up when your within close proximity to the airport.

[officemonkey]

If they really wanted, they would just hold you until you unlocked the phone.