Detectives who work on CSAM cases. They have to watch, document, and describe the offending material in order to enter it as evidence. Then they get undeserved hatred for working with law enforcement.
If they never physically offend, and watching all of it, documenting it, and submitting it puts away those who do physically offend, and it saves someone else the trauma of having to watch it...
Just the iky feeling that they'd be getting off on the videos is what makes me stop short of saying it's a good idea. Like... it's just hard to say okay to something like that.
I'd imagine it would be similar to if porn was banned entirely and you were in a job where you had to view seized pornography. A good chunk of it would simply not be your thing, and the overexposure to pornography would be so bad for your mental and sexual health