Is that a null pointer in a list? :)

It is. The pointer is meant to be a citation for the fact that Florida public schools rank higher than California public schools, but since that is false (Florida is 41st, California 32nd) no such citation exists and the comment is correct not to include one.

I suppose you could say, the parent commenter, by failing to cite a source, has comprehensively cited all sources that support their statement. As you say, a null pointer.