They never said exactly why Klaus was able to reproduce. They simply said it was because of his werewolf heritage. Hope is the only path to new hybrids, so Narducci can run with the lore as he chooses. Narducci seems more focused on the supernatural aspects than Plec. They could be planting a seed, to leave it as a possibility.
If it was said on tvd, I would simply blow it off. Dries has constantly shown her focus is not on the lore or supernatural aspects.