They're bots, so they didn't know how to read. They're fully operated by a system to post an authentication automatically when new thread on bounties section has been created.
I saw some member still wearing the signature until now, I wonder if there is a participant will take it seriously and create a accusation or PMed Brainboss saying he got cheated/scammed
Anyway scam nature in bounty section are based on many factor, even a reputable bounty manager could manage a scam project.
Many scam projects come out so I recommend joining bounty projects that are good at running a bounty. I am more in favor of joining bounty legit and trusted members because they have more experience in choosing legit bounty than newbies because the other bounty managers who are newbie mostly scam projects.