Okay, so I emailed SW to get the "official line"
Here is the answer
Thank you for your email. If a cereal listed in the Food Optimising book states that it has a scan bran or ryvita that is what would be required to make the item qualify as a Healthy Extra. If you choose not to have the scan bran or ryvita with the cereal ( can be eaten seperatly ) the cereal will not be a Healthy Extra.
The foods listed in the Healthy Extras section help to ensure that you get everything that you need for a healthy balanced diet by providing a daily intake of foods rich in fibre and calcium, vitamins and minerals.
It doesn't exactly say you have to syn it BUT it does say that if you don't have the scan/ryvita then it isn't a healthy extra so can't be counted as such.