Shed : I would be wary of placing too much interpretation on those figures, although you make some very valid points.
It is possible that some of those pax are continuing to destinations outside SA but with a gap of greater than 24 hours.
Others may be continuing on tickets sourced elsewhere, for example going to Pakistan using tickets sourced in that country. Ethnic agents in the UK and elsewhere are very skilled at finding the best deals through wide networks of contacts.
Neither would show on the lists that I have pulled, although it would be possible but very time consuming to get such details (which is why MIDT data is so expensive!).
Despite the demonisation of Islam which has been, understandably, brought about by the deeds of a number of fanatical murdering scum, and despite what we may see as primitive and unacceptable practices in some Muslim countries, I would add that I have spent some time in Saudi, and also elsewhere doing some work for Saudia, and was treated with kindness, generosity, and courtesy.