Why couldn't the astronauts meet the president in person appolo11?

The astronauts of Apollo 11, Neil Armstrong, Buzz Aldrin, and Michael Collins, could not meet President Nixon in person immediately after their historic moon landing due to health concerns. They were placed in quarantine for 21 days as a precaution against potential pathogens from the lunar environment. This decision was made to ensure the safety of both the astronauts and the public, given the uncertainties surrounding lunar microbes. They finally met Nixon in person after completing their quarantine period.