Definitive answer: You have absolutely no requirement to every speak to any TSA personnel. They can ask whatever they would like. You are under no requirement to respond to, to initiate, or to continue any conversation.

With that out of the way, of course it is nice for many people to be pleasant. I generally respond to a hello, or good morning. I generally thank someone if they HELP me. I do not thank them for letting me pass or returning my documents.