If an adult pats a girl on the head and says, "There, there--you don't have to have sex if you're immature and you're not ready yet," that's not a viable alternative. That's an insult.
Wendy Shalit, on why tweens shouldn't have to look "sexy":
"There is no longer any mystery or power to sex--it is just expected that everything will be sexual, and so nothing is. There is nothing to wait for, or to look forward to."