I feel sorry for Glop. I have no idea why we have to kill him. He seems to be just minding his own business, mancing his fungi.
If I understood the quest chain correctly...The stone troggs and the Stone Elementals always live in a precarious balance. The latter tolerates the former, but really has no love for them. As long as the troggs weren't tearing stuff up too badly, though, they were left alone.Since the collapse of the pillar and the Shattering, the troggs have gotten fairly aggressive. Not only have they been attacking both the Elemetals and the Earthen, but they've contributed to a sudden rampant and unchecked fungal growth up on the Crimson Expanse. It's gone so far that it's turning Earth Elemental Giants into the Fungal Behemoths that patrol up there. (Not unlike the Curse of Flesh.)Glop is essentially the ring leader in all this and he has to be put down.