Yea, he reminded me of Bartrand and the red lyrium idol they discovered in the Deep Roads... (Dragon Age 2). So, I wanted to see what happens if I free him and when he immediately said, kill Jack and then meet me at Cabot Manor to kill the rest of my family... I was like no Sir and reloaded my previous save and put him down. lol
But yes, true, some here bring up a very valid point - the family kept him locked up for centuries, so I guess, with the help of that artifact, he would build up so much anger and animosity that the first order of business would be to kill them. On the other hand, I am fairly convinced that Jack had a good reason to lock him up in the first place. The world is better off without certain, crazy individuals. Who knows if killing his family would have been the end? I'm sure once that was done, Lorenzo would go on a killing spree that left a bloody path throughout the Commonwealth... the very place I'm trying to re-build, by providing protected settlements - safe havens for those in need.