In a strange move, the Leafs announced this without any details or writeup on the player. The AAV is exactly $100,000 over the minimum salary amount, making it the largest possible contract that can still be on the roster under the emergency exception rules. While that's a good idea for contracts for borderline players, using that rule for Robertson would require him to be in the AHL, and he is not waiver exempt, and is unlikely to clear waivers.
The saga of Robertson's trade demand ends for now, but the low-cost one-year deal is exactly the sort of move that can facilitate an exit off the Leafs in-season.