Liljegren was drafted by an OHL team there was no chance we would trust with the development of a key prospect. Its pretty clear Dubas would trust SSM. I think SSM is the best option. This kid is not AHL ready, and it would be stupid to be overly aggressive with him.
My money would be on Rogle. Small chance the Marlies is an option and he'd need a great training camp for that to happen, like Liljegren. I'd say the chances he goes back to the OHL are even smaller.
By going to Rogle, they can re-assess his play soon after the WJCs (assuming he makes the team) where they can either leave him there for the rest of the season or bring him to the Marlies. Sort of like Nylander and some recent Swedish prospects.
As per an article in Swedish, he does not have an European out clause so the Leafs can send him where they see fit. I assume Sandin will have a say in where he'd like to play and he did mention that he wanted to go back to Sweden next season.