Perhaps it was because Amberser had begun to feel that something was awry, or maybe it was Katherine's pure soul that had finally influenced him, causing him to start feeling that what he was doing was not right.
Sending Airel to replace Aeolus sounded like a good plan, but upon closer consideration, the likelihood of failure was not small.
First was Talos's attitude—would He be willing to watch the scenario unfold again?
Moreover, Airel was not a loner like Aeolus; the Koutao Mermaid Goddess could easily deceive Aeolus, but Airel had a kingdom backing her.
Even if the kingdom had fewer people, the Kuotuo Murlocs were not something they could manipulate at will.
Finally, there was Airel's personality to consider.