RJ specifically said that souls of Trollocs are so twisted and corrupted that they might as well not be souls anymore, which amounts to the same thing. This is keeping in mind that RJ has already said that physical characteristics don't necessarily carry over into another life, so Rand looks different from Lews Therin in many respects, while special mention is made of the souls belonging to the Heroes even though their physical attributes have changed between Turnings.

My money is on the idea that RJ meant to indicate that constructs such as Trollocs have animal souls that have been twisted and damaged, which may be inherently different from human souls. The Nym, seeming to be plant constructs with consciousness, seem to be the result of a different process from Trollocs. Perhaps he meant that whatever you could call a "soul" that exists in a conscious being isn't really present in a Trolloc, even though they have certain characteristics of creatures that would possess a spirit. I just think this is inconsistent.