By Alexander duality, $\mathbb{R^3}\setminus S$$\mathbb{R}^3\setminus S$ has two connected components.
Let $u\colon \mathbb{R^3}\to \mathbb{S^3}\setminus (A\cup B)$$u\colon \mathbb{R}^3\to \mathbb{S}^3\setminus (A\cup B)$ be the universal covering. Denote it by $\tilde S$ a lift of $S$.
Again, by Alexander duality $\mathbb{R^3}\setminus \tilde S$$\mathbb{R}^3\setminus \tilde S$ has two connected components, one. One of them, say $\Omega$ is bounded.
Observe that $u(\Omega)$ is one of the components of $\mathbb{R^3}\setminus S$ and it does not contain $A$ nor $B$.
It follows that both $A$ and $B$ lie in the other connected component ---— a contradiction.