The TSA largely looks for physical evidence that a passenger could be a threat, so they'll generally have no reason to search through the data on your phone. After all, they're the Transportation Security Agency, not a detective agency. Even if they did have reason to want to access your phone, they'd need a warrant.

The Transportation Security Administration (TSA) may scan or inspect your cell phone during security screenings primarily to ensure that the device has not been modified to hide explosives or other prohibited items. Historically, intelligence reports have raised concerns that terrorists could use the internal space of electronic devices to house non-metallic bombs that might evade traditional X-ray detection. While most travelers only see their phone pass through a standard X-ray machine, you may occasionally be asked to turn the device on to prove it is a functioning electronic and not a shell for hazardous materials. It is important to distinguish this from the much more invasive digital searches conducted by Customs and Border Protection (CBP). While TSA's focus is on the physical safety of the aircraft and its passengers, CBP has the legal authority to search the digital contents of your phone—including messages, photos, and apps—without a warrant when you are entering the United States from abroad. This is done to detect digital contraband or information relevant to national security and visitor admissibility.