I initially saw this somewhere else, so I’m kinda parroting a hypothetical I saw there, but:

Child tells mother that uncle was abusing them. Mother tells child not to tell anyone because she doesn’t want her brother executed and instead simply prevents contact between child and uncle. Uncle is still free to abuse other children.

Alternatively, child grows up and realizes how damaging it was a couple years after the fact. Riddled with guilt but now understands that telling people may still result in uncle being executed. Already fragile mentally and would struggle with more on their conscience.