No, you aren't being old-fashioned; you're being wise. After all, no parent would allow their children to wander into a busy intersection or sample the pill bottles in their medicine cabinet. Shouldn't we safeguard our children's moral and spiritual health just as much as their physical health?
Frankly, I feel sorry for your friend's children, because they may well grow up with no real sense of right and wrong–and that will be disastrous. They also may grow up with all kinds of hidden fears and anxieties from being exposed to things they were too young to understand. The Bible says, "No discipline seems pleasant at the time, but painful. Later on, however, it produces a harvest of righteousness and peace for those who have been trained by it" (Hebrews 12:11).
More than ever, children today are exposed to much that is morally and spiritually harmful. And more than ever, parents need to be wise in helping their children turn away from what is evil and turn to what is good. The Bible says, "Train a child in the way he should go, and when he is old he will not turn from it" (Proverbs 22:6).
Pray for your friend and her family, that they may see their need of Christ and put Him at the center of their lives. And may this be true of you, as well.