Can a company auto-terminate you for not working, when they wouldn't approve the surgery to get off worker's comp until now?

After an injury at work, the company would not approve the surgery needed until almost 2 years after the incident. After 1 year, they changed the work status to "Leave of absence" without employee approval. Now the surgery was finally approved, and return to work is within 6 months (after therapy). However, now they auto-terminated employment for not being on the schedule for 180 days, which will cancel out all service-related benefits upon return. Is this legal? Do we have any recourse?