See, I don't think it has to be an "either-or" condition. Of course, security comes first. But customer service can be an important part of the job, as long as it doesn't trump the security concerns.

Customer service doesn't mean "the customer is always right". There are plenty of times that the customer is wrong. It does mean, however, that the customer must be treated with respect at all times, even if the customer doesn't deserve it, and even if the agent must deny the request of a customer at the time.

There are plenty of times that I've called a customer service center and been irate. Sometimes I was right; sometimes I was wrong. My level of anger didn't dictate whether or not I got my own way. But most of the time, I am treated with high respect by the person at the other end of the phone, even if they have to tell me "no". And with the very best staff, I can end up not getting what I want and have my anger dissipated at the same time.

I'm guessing that you've seen situations at your checkpoint where a dispute between a TSO and a passenger regarding a particular disputed item escalated from a war of words to a violent encounter requiring professional intervention. There's no excuse for a passenger doing that, of course. But "it takes two to tango"; I suspect that the general tenor of the encounter got worse as both parties got more and more angry at the other. Once it escalates, the conflict becomes a security problem, regardless of whether or not there was a security problem initially.

On the other hand ... if every TSO is trained on how to professionally handle conflict, without allowing it to escalate, even if the passenger wants to escalate it, there will be fewer security incidents. And that is the whole point of the TSA, right --- to make flying more secure?