Perhaps, but I could equally say you are letting classic liberal ideas get in the way of your practical reason/ common sense.
We supposedly all have the right to do what we want as long as our actions do not negatively impinge on others. And for the sake of the argument, and with adults in mind, I concede that.
But we are not talking about adults, so the liberal logic does not apply. Isn't a child's access to pornography going to have a negative impact on their life? Yes, because they are not yet the developed, free, rational, independent person/ agent that the liberal theory has before it in its model of society. This is why all liberals SUPPORT having laws to protect children. This is why there are laws prohibiting the sale of cigarettes and alcohol to minors.
Put your prejudices to one side for a moment and think about it.