it doesn't benefit shea to go around killing customers so it would probably be a one-off just to set precedent in a new city as a sort of "do not fuck with me" tone, and it would only be if he was owed a LOT of money that he didn't think he was going to get back. he was probably willing to pay well for her to not ask questions and he would tell her to keep his number if she ever needed to make some extra cash again. he's not "friendly" so to speak, but he would like her because she's beneficial to him so that's the closest thing to friendship with a human he really does, haha.