What happens to Mulch after he checks in on Holly and she informs him that she cannot leave?

Mulch propels himself underground, going for a while before realizing that no one is behind him. Now is the time for his escape plan. He alters his course to the rabbit warren that he'd noticed on the way in. He breaches the tunnel wall, but is careful to look the other way so that no one on top can see what he is about to do. He waits and as soon as a rabbit approaches, he grabs its neck. With one hand he brings the earth crumbling around him and with the other, he puts his iris-cam into the dead rabbit's eye.