I found out about this signature from the YOBIT mailing list. https://yobit.net/en/signature/details/ There are no such requirements in these rules. How do I know that the bounty gave Yahoo?
You are not posting on Yobit. You are posting on bitcointalk. Bitcointalk has its own rules and you should be aware of them as you are a member of it.
Also, Yahoo62278 is the manager of the campaign you were participating in and you should pay attention to the rules made by the manager.