Procedural due process in termination of employment cases

Dear PAO,

Is the requirement of due process in dismissal of employment cases complied with if the same is done through a text message? My nephew presented the text messages he received from his boss informing him that he no longer need to report for work and instructing him to report to the HR Department to process his clearance and backpay. According to his boss, as a probationary employee, he doesn't enjoy security of tenure.