Even if there was some technical immigration violation here its not like any of the people involved were some sort of flight risk or criminal masterminds. They

Even if there was some technical immigration violation here its not like any of the people involved were some sort of flight risk or criminal masterminds. They could have simply notified the company and the people about a potential problem with their visas/paperwork and asked them to provide documentation otherwise or if their visas were expired/improper to return to Korea and apply for a new visa.