This could work, and rest assured, several families have tried this. However, it is greatly unhealthy for a child to be sheltered from society for a majority of his or her life. Sheltering a child is essentially hiding the child from the truth and forming a false perception of society. A more logical approach to this complex problem is through communication. Merely explaining to the child that what is seen in movies and television is only for entertainment purposes, and in most cases is dangerous if ever practiced, exposes the child to society as it is.
Education is undoubtedly the key in governing a child's development.
Education is an ongoing process and in most cases takes several years for a young child to understand the basis of entertainment. But it works. Free will is a powerful thing, and when used on an educated and logical level, can be even more powerful. Sheltering a child essentially is removing the element of free will, which provokes adverse and detrimental behavior. In the end, it seems as though the debate will continue in a whirlpool of circular reasoning giving rise to little conclusive evidence.