Coming out of Mormonism I would say that was doctor Laura like advice. No need to hurt them, just protect the child.
I moved to Utah 8 years ago and sent my oldest ahead to my sisters who is Mormon. They all tried to tell him about JS behind me and my wifes back knowing she (my wife) was Catholic, that my son was Catholic. I became Catholic the same year. You really have to be careful.
If they can learn the Catholic faith at a young age this is very good. It may not see them through but as they get older this is where it will help. I know many Catholics here in Utah that became Mormon then came back home after learning their theology. As long as they know the theology of Christianity they will know the difference. One of the most important things they need to know is that God is Creator, we are Created. That Jesus has first place over even our families. I tell my children that I will fail them at times, but Jesus never will. He is different than a human father. His love is un conditianl as He is love itself. These things will help
God Bless
Rich
www.utahmission.com