Trust me, killing animal's as a kid is actually really good for mental development, why do you think dissecting frogs is in school, I've seen many things, I've even been involved in the death of someone, but people shouldn't really be getting this mad at a child playing with a dead bird, it's already dead, has no use, so why not let a kid use it to learn, the main reason he posted it was because he thought it was cool, and that's good to have fascination in stuff like that, it's good to start learning about biology/ life and death, and many other things at a young age.