What was the main intention of helping micheal with the surgely 由 the General?

This bastard(sorry for being rude)Krantz decided to help Michael only because of bringing back the "treasure" of the company, Scylla.

The General wanted Michael to 加入 the Company and work for him. He probably arranged for Michael to have surgery because he wanted Michael to feel as though he owed the General something and wanted to brainwash him into working for them.