This is a fallacy that everyone at NASA would have needed to be "in" on the conspiracy. During Apollo 11, the Parkes Observatory had full control of reception, recording & transfer of audio, video and telemetry. The Manned Space Flight Network (MSFN) comprised a few other tracking stations such as Honeysuckle Creek, Goldstone Station, Tidbinbilla, etc.
The MSFN simply relayed the signals it received over the landlines to the technicians at the Mission Control Center (MCC) in Houston. These technicians didn’t need to know or care where the data came from. The MCC were trained for actual space missions by being fed simulated data over the landlines- explained in the documentary, "Failure is not an option". Furthermore, the technicians wouldn't know the difference between a simulation and a "real" mission. Hence there is no need for them to ‘keep quiet’ about anything.
http://www.parkes.atnf.csiro.au/news_events/apollo11/parkes_operations.html