Part of the strategy to survive successfully in life is to know when you can win the war and when you are against a superior enemy.

Waring against the TSA is a losing battle.

From the story, it appears as if they were agreeable with the concept of having her bring an empty sippy cup through. She should have been apologetic, like saying sorry to the Stasi or KGB in order to be let out of secret police custody.

Recently, a TSA agent disallowed by bottle of sunscreen but then let it go after seeing it was 4 oz. and asking me to check it in on the way back. Yes, of course, sorry, thank you instead of noting that it was almost empty. Fighting that battle is not one that can be won.