>Virginia law prevents six-year-olds being tried as adults. And the child would also be too young to be committed to the custody of the Department of Juvenile Justice if found guilty.

Correct, and also (like you said), state law prohibits anyone under the age of 11 from being sent away to Juvenile Hall.
(The parental rights can be taken away from the parents at pretty much any age)

There's a general argument that minimum age of 11 is because, in effect, 5-6 year old kids never do anything that rises to the level of a criminal offense....in layman's terms, no need to have laws saying you can arrest and charge a 5-6 year old with crime, because....5-6 year old kids usually don't do anything that serious.....and in the rare cases, where it happens, it's an accident. Well, this case might wind being unprecedented in multiple ways.

(I'm not saying kids that young should be charged....they shouldn't....but I won't be at all shocked if some relevant aspects of this case are put under a microscope while other relevant aspects of this case are swept under the rug. I say that as a parent of a kid in the public school system).