This was exactly what the Oryx King feared. He didn't want for the Oryx to suddenly be forced into a situation where they had no choice but to become the warriors of others. As for Leonel's comments about his cowardice, if such comments could faze him, he would have long since changed his approach to ruling.
People who could call themselves Kings wouldn't easily change their mind about such things.
As for Leonel, his mind had been made up. He had been too nice for far too long.
Even disregarding what he had done for the Oryx Kingdom, back when Valiant Heart Mountain was being attacked, it was he who gave them a path to survive. Afterward, he invested a large amount in their development through Elthor to ensure that they would take full advantage of their Hyper Evolution stage.