GBZ, I think that he is doing a taster menu of all three services. With a
PR coup like this I doubt that the cheeses will train him as a Radar op or a Rock ape, so he'll train as what the RAF is best known for and where it will get the best photo opportunities.
Also you can imagine what Prince william would say if he was told that he would spend 6 mths as a dog walker during his acquaint with the RAF.
I don't think it is all about him getting wings (from his point of view), I think it is about him doing the most interesting job in each service.