Can an employee be fired for missing work during quarantine period required by company?

Since the pandemic has started, my friend has missed work more than usual which has led to tension between them and their employer. For context, the business was recently acquired by a national corporation and is located in North Carolina.

The company has threatened to reduce the position to part time (with no benefits) or to outright fire my friend. Ordinarily this might be justified, but the kicker is that they required my friend to stay home and quarantine for 7 days, which added significantly to the total number of days missed recently. My friend also mentioned that not everyone in the workplace is being held to the same safety/quarantining standards. The manager (corporate hired) recently returned from a trip to Myrtle Beach and did not quarantine at all before returning to work. As North Carolina has no required quarantine period, there’s no issue with the manager immediately returning, but requiring other employees to do so and then punishing them for it seems inappropriate.

Besides looking for a new job (which is difficult considering the current job climate), how should my friend handle this situation, and is termination on the grounds of missing too much time due to a quarantine even legal?