Originally Posted by jkhuggins

Okay, so let's recap here.

1. You were found to have a sippy cup of water in your carry-on, in violation of TSA's (nonsensical) rules.
2. The screener offered to test the water, in accordance with TSA's (nonsensical) rules.
3. In response, you asked to screener to dump the water --- which TSA employees are not supposed to do. The screener agreed to your request.
4. When the screener attempted to voluntarily comply with your request in a way that displeased you, but which you had not specified, you cancelled your first request and asked the screener to discard the cup. Again, TSA employees are not supposed to discard items for passengers; passengers are supposed to do that for themselves. The screener again agreed to your request.
5. After the screener performed your requested action, you asked the screener why she didn't perform the first request the way you had assumed she would. She gave you an answer, which showed that she was trying to be considerate for the cleaning staff in the airport.
6. You disliked her answer and challenged her reasoning. She disliked your answer and challenged you.

Sounds to me like the screener was trying to be professional towards you, violating TSA rules left and right, until she finally snapped unprofessionally at you. Yes, she shouldn't have lost her patience with you. But, sitting here safely behind my computer screen, it seems to me like she showed a lot of patience with you right up until that point.