How does a layoff affect seniority for someone receiving workers’ comp benefits?

Q. We have an employee who had been performing light-duty work for more than six months. We laid him off based on his seniority. Now he is receiving workers’ compensation benefits again. Our collective-bargaining agreement provides that an employee will lose seniority after being laid off for a year. Does the fact that our employee is receiving workers’ comp benefits have any effect on his seniority rights?