The problem with that is if you run into the wrong guy it might get you killed.

I think that seems a bit extreme. I've opted out of nearly every flight I've been on (unless crunched for time due to traffic of crazy lines or something) and I've never been treated like this, I'm not defending the TSA, I'm just saying this isn't "normal". Sometimes they'll make you stand around and wait, the shoving and the intimidation has never occurred. Making the jump to the idea that a TSA officer has a weapon, or can "issue a hit" is absurd.

edit: Also, the most shocking part of the whole ordeal is usually the looks from the OTHER people in line, like they think you're going to be killed or assaulted, or "why don't you just cooperate, it's easier". That's the part that really makes me sad.

Right. Complaining about a TSA agent (who isn't law enforcement) shoving you is going to get you killed. Hyperbole like this helps no one.

You should even be able to complain about being assaulted by people who are law enforcement without fear of fatal retribution.

I was talking about if it escalates to the police being called. Would you have us believe there have been no mysterious deaths of people after being taken into police custody? Note I am not saying you are likely to die, I am saying it can and has happened.