I believe that is not because they disavow an entire bad website, but due to the fact that they are disavowing links that were actually assisting them. Using the disavow tool as a machete, in a broad spread method for a domain, if you know those links are not assisting you (not sure how you would understand precisely) then it wont injure. If you disavow one link that is assisting you, sure – that can hurt.Overall, you probably do not require to bother with the disavow, but you can – according to Google.Forum discussion at Twitter.