The current goal seems to be: eliminate anything that might be objectionable to anyone, ever. The approach is: expose underpaid drones to every instance of objectionable content conceivable. To do this to people in Africa is especially unconscionable, considering how much of this stuff hasn't been that far removed from reality for them and their neighbors in recent history.
Why are queries being policed at all? This makes no sense. It's creepy voyeurism leading to complaints about trauma from seeing something you wish you hadn't.
Just review the responses people complain about. If someone asks for obscene content and receives it, why is that even a problem worth reviewing? If someone asks for brownie recipes and gets fetish erotica, that's more of a problem needing review, and the reason why is undeniably clear. There is a point to exposing unwitting moderators to it, and their suffering through it at least serves a purpose.
If the goal was total moral purity, don't train on "bad" inputs indiscriminately. Train on NPR.org and ignore the rest of the internet. Everything about this seems so backward.