Why Kindred are enemies of most Shadow Isles champions?

The Shadow Isles is full of the undead, those that cheat death. Essentially, they're things that have escaped Kindred's grasp.

Because the whole thing about the Shadow Isles is that they fuck with Death.

Shadow Isle champions typically don't enjoy the idea of death.

Where all who die are supposed to meet Kindred in the end before passing on, those taken by the Shadow Isles never meet them, and their souls are imprisoned or enslaved against their will.

Kindred doesn't like this.