Currently, all the genetic beasts in Sakura have already arrived on the island. If they didn't kill the white monkey, these genetic beasts would die in its hands sooner or later. According to Merrick's previous hypothesis, those who could tame the 03 series genetic beast were at least geneticists of the same series, or even stronger.
Coupled with Su Yun, who was suspected to have undergone a natural genetic mutation, it was very difficult to evaluate this person's strength using any reference template that had been developed. After all, he was not artificially modified.
In addition with the grudges they had formed a few years ago, Su Yun had long become a knot in the hearts of the overseas factions. Hence, be it Su Yun or the white monkey, they had become the target of death in his heart.