You are asking the million dollar question. I have no idea what the correct answer is. I will let you read the data and come to your own conclusion. I wish somebody would post some pictures of some early REWISes. From the 1830 census and forward, John and Mary Rewis and their descendents have always been enumerated as white people.
1880 is the only exception that I have found. In this census James Jackson Rewis, son of John and Mary Rewis, was enumerated as a mulatto, along with several of his children and grandchildren. However, before and after 1880, he and his children are all enumerated as white. Go figure.