Marks point is that just because no one said anything at the time does not mean nothing happened. To use it as proof that nothing happened is a logical fallacy.
Where am I saying nothing happened?! If someone says they have been assaulted, then it needs to be investigated. Comparing it to Saville makes it sound like you are saying there was a culture of child sexual exploitation.
I was just translating Mark's (sledgehammer) example as you seemed to misunderstand him.
It wasn't a comparison with the Saville case, the Saville case is an example where some people only came forward at a much later time when the wider picture came to public attention.
Marks point is that just because no one said anything at the time does not mean nothing happened. To use it as proof that nothing happened is a logical fallacy.