Will there be a Fair Usage Policy in place for the nbn™ Sky Muster™ satellite service?

Yes - the Sky Muster™ satellite service does have a Fair Use Policy in place to ensure fair access to the services over the new satellites, including during peak-usage times. This Fair Use Policy applies between nbn and the internet service provider. The internet service provider may have a separate fair use policy which applies to premises.
Satellite capacity is a finite resource and nbn is working closely with internet service providers to ensure they manage capacity properly.