Considering star wars cost him his marriage i can understand why he has a love/hate relationship with it and treats it solely as a method for a cash profit.
I can also understand his hatred of Empire because it going over budget made him have to go back to Fox to cover the guarantee of the loan, did not fit his vision of a faster and more action packed sequel like Jedi did and on the cheap.
Also if it failed and did not make back its money the Ranch Project was in jeopardy.
Allegedly he considered firing Gary on star wars, he put it off. Considered firing him on empire and put it off. Made sure he was not involved in raiders or jedi and was let go.
lucas came pretty close to taking the film away from Kersh and reassembling the footage to fit his vision. Lucky for us the way he cut the footage did not work. And Kersh was able to finish his film.