A viewer develops the idea that appointing Tilly as executive officer lets Saru keep Burnham as his informal problem-solver. The proposed advantage is plausible deniability when Burnham acts independently. On this reading, Saru models himself on great captains of the past while recognizing that he does not behave like them. Burnham supplies the freedom of action he needs without holding the formal appointment.
Notable Point · 2:22:34-2:22:58
Saru, Burnham and plausible deniability
One interpretation of Tilly's appointment gives Saru formal control while preserving Burnham's informal role and freedom of action.