Currently, the only people who know the secret of the Energy Secret Technique are likely the high-ranking members of the White Feather Gang. And now, apart from Isaac, all the others have been dealt with by the Defense Corps, meaning Isaac is the only one left who knows the secret.
If Isaac still harbors the ambition to rebuild his forces, he will certainly guard the secret tightly. But there's no guarantee that his ambition will continue, and he might use it to exchange for resources and benefits.
If that happens, his situation will become perilous.
After all, he now holds a great treasure, and in the Mist Mountain Region, he's not invincible. Should he divulge this secret to a force like the Smiling Skull, and if they believe him, he could face a catastrophic disaster.
To resolve this issue, the only option is to eliminate Isaac before he leaks the secret.
But right now, eliminating Isaac is not an easy task.
