There're always BS and politics in show business even till today. Bruce Lee faced racism in Hollywood which was why he was not given many opportunities there. Let's face the fact, in 1971, he's only one man and even with a lawyer, his force is too limited to do anything against big GIANTS in the Hollywood let alone thinking to get his rights by suing ABC Networks or Warners. These big parties are financially strong with legal groups of consultants.
Bruce was a smart guy with high EQ, instead of wasting time fighting for his legal rights and killing himself off in the market, he must well moved on. He made the right choice or else there wouldn't be partnership with Warner in making the internationally recognized ETD and realizing his dream of becoming the biggest Oriental star in the world.