Am I confusing something? That looks like Linux guest support on a Windows Server host, which is rather different to the Windows Container topic of this thread.
I think that the goal was to show that Microsoft already supports the Docker orchestration stack with its current products - and in doing so is laying the groundwork for integrating future Windows containers into that same stack.
[1] https://docs.docker.com/swarm/ [2] https://docs.docker.com/compose/