...No, it could harm plenty of things to check, if for example they captured her and used magic and torture to force her to reveal all she knew, and then used her as base material to create hundreds of carefully crafted slaves with all her mental powers but a conditioned loyalty to the Dark. That would harm many things indeed. This particular Endarkened has developed no magical skills or tricks that might alert him to a mental intruder or allow him to deal with one, but it is not out of the question that such magic might exist, having perhaps been discovered sometime in the past ten thousand years while he was living on this island cultivating toxic wildlife.