This is certainly a fair argument and is reasonable. Though, my question is, what do you want Watchtower to do in countries that either have a low age of consent or have a very lax or non-existent law enforcement and judicial branch. There are countries out there that do have a low age of consent and even some states in the US that do. Watchtower makes policies for a worldwide organization.
That's irrelevant - yes Austria ( for example) has a lower age of consent than is normal. If no crime has been comitted then it shouldn't need to be reported to the authorities if a case comes to the attention of the local elders. Where a crime has been committed though and the victim is still underage, then reporting of it should be mandatory. It's not rocket science. Every other organisation, from youth clubs to the scouts manage to have proper safeguarding policies in place regardless of the variation in local laws.