I trust what a TSO says as far as I can throw them and I am pretty strong. What your friend was told is read from a TSA guidebook. TSOs love calling actual police for drugs, forbidden items and yes even overstaying visas. It is far outside their purview but gov't agencies thrive on mission creep. They are after all on the "front lines".
In today's political climate it is riskier and riskier to travel while lacking legal status or proper visa/waiver. TSA & CBP have stepped up their random checks while airside which can be more thorough of documents and questions about travels and then status.
Originally Posted by
ybanag
A friend in the same situation who travels a lot for his company has asked a TSA manager the same question and this is what he was told.
TSA is a counterterorrism organization and their main mission is: "Protect the nation's transportation systems to ensure freedom of movement for people and commerce."
They do not check your legal status. As long as you present a valid Foreign passport, Federal or State issued DL or ID that matches the name on your boarding pass.
Even if you forgot your ID you are "ensured freedom of movement", you just have to go through additional screening.