@Becca30 the host might be willing to refund you, but there is no guarantee he will, and he can't make Airbnb refund their service fees. He can change his minimum stay for those nights and then send you an alteration request (or you can send one to him).
But no, it is not normal for a new host to take over an established listing and its reservations. In fact Airbnb terms of service specifically prohibit this and Airbnb makes it very hard to violate that rule. It sounds like he doesn't know much about Airbnb so he, and the new owner, may not know this and they will be in for an unpleasant surprise.
Unless you are really, really set on staying in this particular place, I would tell him that you are uncomfortable with the sale plan and ask him to cancel the reservation for you. If he won't do that, I would call Airbnb and ask for a penalty-free cancellation on the grounds that the property no longer belongs to the host. Then I would find another place to stay.