Does a first grader really know what 'kill all the Chinese' means? It was just a stunt performed by a child - a demographic known for risk taking and attention seeking. I doubt seriously that the child actually thought his suggested solution was a workable one. We have to stop judging him as though he did. Context: It's important. Humor: Not everything someone says is something the mean 100% -
especially if it's said for the sake of humor.
And if Kimmel said it marching with posters depicting him as Hitler would
most certainly not be ok ... unless he actually meant it. See, Hitler didn't
joke (important word) about genocide, he actually tried it. That's what some may consider an important difference.