Josh does need saving (or exposing) he told Moira and presumably the police that Matty came at him with a knife which is untrue, he also said on the phone that there had been a stabbing, not an accident. Then he told Jai to keep Matty away from him, suggesting that Matty had been the aggressor. Samson now has to decide whether to back up Josh or Matty. He pushed Samson hard to wards someone holding a knife, that was reckless, so there must be something he can be charged with