The Blood Moon Lord's method was quite straightforward. Since any appointed as the leader of the Beastmen could potentially be assassinated by the players, he decided not to immediately appoint one at all. Once the players retreated, he could safely arrange for a successor without the worry of the new leader rapidly meeting their demise.
The outcome was not particularly beneficial to Zhou Tian, but what provided him with some comfort was the pledge given by the Blood Moon Lord. It gave Zhou Tian hope for attaining the leadership.
Since the Blood Moon Lord did not plan to prompt the appointment of a Beastman leader, he used the position as bait. For the sake of the Beastman Clan, he sent out a team, not overwhelming in power but reborn as Beastmen, to lend aid to Zhou Tian's cause.