Completely sympathize. I had an experience in my black hat days - broke into a server and found folder upon folder of JPG's. Stupidly downloaded some of them and opened the first to find an image so disturbing that I can't even begin to describe it.
We were a bit conflicted about what to do (more how to do it), and ended up reporting it to both the US and Australian feds (which I suspect may have given me a free pass on one of the crazier things I later did).
I really didn't take it well, but one of the guys in our group was inspired to start a vigilante group that would hunt these distribution networks down and it achieved some success in the 90s.
Hopefully these employees can be eventually protected with some basic level of ML that would filter out the worst of the worst (apparently Microsoft Research have a well-developed fingerprinting system for child exploitation images) - because i'd really hate to imagine the scenario you and Chen describe, and what I briefly experienced, as becoming more common.