Of course I agree with Pete and others that Michael wanted Anthony in his business and as his successor. The scene was vintage Michael the Manipulator--a contest of wills. Michael threw in the line, "then you can do whatever you want [after law school] as a sop to Kay, to (unsuccessfully) get her on his side, and to weaken Anthony's resolve. if Anthony had agreed to go to law school, it would have been a capitulation to Michael. He'd never be able to escape Michael's clutches after that.