I'm not following your train of thought here. Since null == null in json-land there isn't a need for or concept of "is distinct from". We tend to not expend space on pointing out things that don't exist.
But you said previously in this document about IS DISTINCT, so it's related to NULL. I thought it would be better to mention that here, for JSON PATH, that way doesn't exist.
"JSON null value is considered equal to other JSON null values, so here we don't have the IS DISTINCT operator"
