They did not lie!
They gave you a very creative version of the truth...
1) The gate agents actually get a "electronic message", that advises them to start checking carry-ons!
It has nothing to do with sensors, though.
It is the QiK over SABRE-interface, that shows a message after a certain number of pax has been boarded, without considering the actual sizes of luggage.
So...no lie, the message came electronically.
2) The FAA will approve all aircraft types and their interiors, before they may be used commercially in the U.S.!
Therefore the bins were regulated by the FAA at some point.
That has absolutely nothing to do with that certain flight of course.
But, again...no lie!
You fell for political BS-speech!