To take your arguments to a logical conclusion, children should be banned from the internet, not allowed near a chat room, not allowed on any site that is not owned and policed by Disney.
It seems that you are not actually worried so much about the children as much as the chance that they may falsely accuse someone else.
If you read the guidelines of the new policy, you will see that children under 16 will be allowed ONLY on supervised sims, and older children, 16+ are adults in almost every country but the US, and are considered adult enough to make their own decisions.
It is quite easy to get someone banned from SL by making false accusations of many types, the new rules do not make this any more likely in my view.
Children are merely people who have not learned as much as an adult yet, they are not a dangerous breed of animal that we have to be protected from.
Just a thought, you have the ability to save all chat and IMs, also, LL has a record of all chat and IMs, that can be used in an harrassment proceedings, if you are worried about the chat being in voice, then dont use it