Spot on Check Airman.
FLX/MCT- while taxying you can turn the TCAS off while leaving your transponder operating if required by local procedures.
Speaking only for Airbus their FCOM 1.34.80 states in part that "... if windshear, stall or GPWS are triggered or aircraft below 500ft agl all TCAS aural messages are suppressed." (minor alt differences depending on whether climbing or descending).
Drivers of other types can speak to their specific aircraft.