An employer whose establishment was closed on Saturday or Sunday to comply with Chapter 15, Acts of the 57th Legislature, 1st Called Session, 1961 (Article 9001, Vernon’s Texas Civil Statutes), before that Act was repealed effective September 1, 1985, may not require an employee who has been continuously employed by that employer since August 31, 1985, to work on whichever of those days the establishment was closed.