Angor quite admired Pierre's effort for providing his slaves, who were also his friends, with a better future in this cruel world. Jon once lectured him on the subject of human rights and similar affairs. Regardless, Angor already knew that the wizarding world did not obey such mortal disciplines.
However, he still appreciated it that someone like Pierre was there to strive for the better.
Angor assumed that most of the slaves here were homeless wanderers who once lived better lives. They were lucky to have found Pierre, who was quite different from the common slavers found in this world.