I've come up against a brick wall in trying to find out anything further on this mission, including e-mailing a couple of the investigators linked to the project (no responses to date) The mission concept is very intriguing, but it seems to be very much on the back-burner - at least 5 years of being in the 'concept' stages.
It would be a shame if the mission never flew, as it has the potential if successful to improve our knowledge of how an asteroid's orbit changes following an impact, and also to provide in-situ science of the material excavated from beneath the crust.
Ilbasso: The website blurb states that an AMOR asteroid would be targeted (i.e one that is well outside earth's orbit), so they're taking no chances with any stray debris
Jase