It would be an interesting argument whether an employer has the right to demand an employee complete a duty which then results in mandatory quarantine.
There are various human rights that protect an individual from being detained including for the case of disease control. I understand that a crew member may be prepared to waive these rights if they wish to work however I’m not sure that an employer could enforce a work contract that would, as a result of crossing a border whilst working, create a situation where the employee is forced into detention thereby having their human rights breached.
If anyone knows the answer I’d love to hear it.