Mmmmh this is a good question. Black holes are governed by gravity. As gravity is the same in both the visible and mirror sectors, black holes do not really care about particles being 'normal' or 'mirror' particles. So in short, black holes provide a link. But this link is one of the three possible ones (see also my answer to the comment of inertia in this post).

I hope this clarifies. Otherwise please let me know.