Let me put on my tin foil hat for a moment: Tor being anonymous, there is no way to know whether what you saw was a.) authentic content created (mostly) by actual child molesters b.) excellent copy written to cause maximum outrage against tor by some entity that does not like tor c.) somewhere in between, e.g. making sure that you actually stumble upon CP every once in a while when using onion sites

While b is not very probable, I can actually imagine that c is a pretty easy option to put many decent people off using tor.