Realize you are dealing with people essentially in a customer service position (but with little or no accountability for delivering said customer service) who think they are cops. Since it is the TSA, you are in the US and have rights granted to US citizens.

Don't raise your voice, and calmly state you feel more comfortable in a location where you have clear visibility of your posessions and want to make sure your possessions are in a secure location. Then don't budge until your possessions are secure.

They can make all the noise you want. Keep your voice down and if need be, ask for witnesses to stay a few moments to back you up. A LEO won't be far away and will find your request reasonable. If a TSA screener is screaming hystarically that you are beligerant, and you are calmly standing there wanting to protect your posessions, you are likely to be believed.