As another poster pointed out, even Amish children know who Madonna is. And as a society we've almost reached the point where you do have to become as isolated as the Amish in order to raise your children with good morals.
Let me try to speak libertarian to you. The shared morals of a society are an externality. If those shared morals are negative then the statist solution is for government to regulate them. The libertarian solution to externalities is private ownership. The person who lives downstream from a factory sues them for the cost to clean up the river in his property. The Howard Stern libertarians in this thread are like the factory lawyers. They feel entitled to pollute their own private property as much as they want and they don't care that doing so imposes extra costs on people who have children that may swim in that water downstream.
When someone says "The government ought to" what they mean is "We shouldn't have to" and that, Sir, is socialism.
When the government controls TV, how long will it be before "separation of church and state" (meaning the right to separate your children from religion) will claim that religion shouldn't be fouling the airwaves? I mean, atheists won't be able to keep their children from seeing that!
Whatever you let the government touch becomes the property of the government.
The difference here is, whatever pollution the Howard Stern factory might be spewing, the people downriver are voluntarily paying to be exposed to such pollution.
Subscribing to cable television is a wholly voluntary activity. Nobody is exposed to the pollution against their will.