I'm sure children can distinguish fiction from reality better than adults give them credit for. Sure, it's possible for a kid to mimic a violent kid's show from time to time. But such incidents are rare, and seem to coincide with poor parenting for the most part.
That said, I find it reasonable to think that children may have an underdeveloped capacity to understand sophisticated phenomena such as social norms. I remember that I didn't truly understand the dynamic nature of social norms till middle school. Children can be quite trusting when it comes to moral instruction. In that sense, perhaps one can justify "sanitizing" stories for an audience with impaired discernment.
That said, I find it reasonable to think that children may have an underdeveloped capacity to understand sophisticated phenomena such as social norms. I remember that I didn't truly understand the dynamic nature of social norms till middle school. Children can be quite trusting when it comes to moral instruction. In that sense, perhaps one can justify "sanitizing" stories for an audience with impaired discernment.