I asked for it a got the following as the official word from Safari on the snorkel for the Diesel WJ/WG is:
Very unlikely, sorry.
While the OZ Jeep market does not justify the non recurring expense for either, obviously the petrol variant is off set by the US market demand.
With no such requirement from the Yanks for the diesel, the business model just cannot stand up, sorry,
...so it seems that those WJ/WG Grand CRD owners who want a snorkel will have to go with the Airflow option when it's available.
(again, plase don't shoot the messenger
)