Kampfer has been very good, but at the same time he's been "injured" for a while. If he can come back, then great, otherwise, get him the surgery he needs.
In the meantime, this is a perfect opportunity for Matheson. There's no pressure on this game and a chance for him to get some more experience.
I assume Gudbranson will be at the least ready for Game 1, if not Kampfer. And unless Matheson really impresses, I would assume they would sooner have Dylan Olsen play as the 6th D for sheer experience alone. This also assumes that Mitchell does not come back, and he probably shouldn't if he his health is in that much danger.