Maybe in TV/film, but in theatre often the contract either comes while the show's running or never at all. You work on good faith from both parties, particularly if you're powerful, until someone gets around to finally drafting the contract.
As if Cameron hadn't had his diary cleared for months to be around during the cast on stage/previews period! He's the producer, after all - he (and his office) are the ones that plan the schedule. He really needs to go "the whole Hal Prince" - be producer and director. He'd get what he wants then.
As for Tim Sheader, even if he didn't do the greatest job in the world, what can you do in the face of a multimillionaire toddler who can fire you any time he likes if you don't say yes, who has you directing a show that is by all accounts pretty poor on the page, let alone on the stage?