Chris, that is my concern. I think the quill is strong enough, but the morse taper is not designed for lateral forces, and will drop out. At the same time I wonder if technique can overcome this - for example, plunging down along the mortice, and only cleaning up when there is minimal material to remove?
Note that I am not considering the drill press as a mill (such as levelling metals), but rather to "mill", that is, clean out the wooden waste in mortises.
Regards from Perth
Derek