TSA Security Directive SD 1544-06-01D
All uniformed crewmembers (working, deadheading, commuting, or pass traveling) are exempt from the restriction as long as they are in uniform while on airport property. This means the secured side of the terminals, all areas accessed with your SIDA badge and/or Crew ID Badge, and includes the aircraft while parked at the gate.
TSA may conduct random security screening at all areas of the airport property, including gate areas and operation areas. If a traveling crewmember is found to have liquids in excess of the limit, and is not in uniform, then they would be in violation of SD 1544-06-01D. They could be cited and assessed a civil penalty by the TSA. To avoid this, crewmembers must remain in their uniforms while on airport property if they are in possession of liquids beyond the limit during their travels.