The setup is giving the impression that once integrated the thing is going to be big. So the Professors might be doing that because it's actually going to be smaller...like human size. Loving Spouse proposed one specific human, in fact: someone we haven't seen in a long time, who'd have a reason to go after Klaus, and who the Dreen would want to keep Agatha far away from when they try to kill it. Him, I mean.

It's an extreme long shot, admittedly.