Walt told Gus he was quitting after he sold the 38 pounds to Gus for 1.2 million? Remember Walt went to Pollos and told Gus "I am not a criminal, I am making a change in my life." Then Gus offered Walt 3 million for 3 months and Walt still said no and Gus shook his hand and Walt left.
Would Gus really want Walt just walking away like that after knowing who he was?
I think Walt didn't pose an enormous threat to Gus's own operation, so he didn't need to kill Walt. He knew Walt was dying anyway. Besides, if he left the door open, Walt could change his mind. I think Gus's goal was to have Walt teach Gayle to make the blue product.
shareWalt didn’t really know anything about Gus. Also Gus never even made the deal, Victor did. Walt could have gone to the police but with what? He never witnessed Gus doing any wrong doing, just knowing that someone is a criminal isn’t enough to lock them up, you need to have actual evidence of them doing illegal things.
shareWhy would Walt do that? He was guilty of cooking the meth. He wouldn't volunteer that information to incriminate himself.
Besides, Gus had a feeling he could convince Walt to cook more for the right price.