From what they did this past episode, it might be possible that the sails are not for sailing the solar wind, but as power gatherers. And the propulsion system something more along the lines of ion drive, which can go very very fast, but it takes either a lot of mass, or a lot of time to get to those ridiculous velocities. I say this because
It wasn't that they used the sails to blind the enemy, but that the sails all of a sudden seemed to have ghost sails that greatly extended away from the ship. Changing the aspect and sail plan from what they were using to follow their course would mean that they would change directions drastically when they moved and opaqued the sails.
But perhaps they were leaving something so speculative to the future, knowing that just about anything they could come up with would be wrong in some regard. This way they can say that how do we know something like this won't exist, rather than propose a solution that may prove to be completely in error. Famopus case in point, Jules Verne's bullet to the moon. Sure you can do that, but your passengers will be paste during launch.