Can an employee determine their return to work date after 10 day self-isolation?

Hi there,
An employee tested positive for Covid and has completed their mandatory self-isolation. They were due back to work April 08, 2021 but has notified that they will not be returning to work until May 01, 2021. As far as I know people do not get to pick their return to work date, however, given it’s Covid related I wanted to double-check if this is viable or not. To be clear, this extra time off was not mandated by Fraser Health or their doctor (no documentation has been provided to us).
Can we “order” them back to work since their isolation is over? 
Thank you