In the second case, you only need to construct enough alternative outcomes to certify your claim. In the first case, you need to prove a universal statement about all possible theories.

All these arguments are at best suggestive. Our abductive capacities are such as to suggest that proving a universal statement about all possible theories isn't necessarily hard. Your arguments, I think, flow from and then confirm a nominalistic bias: accept concrete data; beware of general theories.

There are universal statements known with greater certainly than any particular data, e.g., life evolved from inanimate matter and mind always supervenes on physics.