Nevertheless, as this young man was in the eye of the law not a man, but a thing, all these superior qualifications were subject to the control of a vulgar, narrow-minded, tyrannical master.
This line is quite telling of the hate and prejudice that enslaved people experienced, instead of celebrating him or just allowing him to create more inventions, instead he starts to abuse him out of jealousy because he views him as inferior. So the boss does what is allowed under this system which is hurt him.