We have thousands of posts every day and only a few admins who simply are not able to check every post not talking about pm's...


I think you should remember what is the main purpose of this site - it is a discussion forum! Not a specialized platform developed for conducting secure transactions or bounty campaigns. The bounties threads on altcoins board are not bitcointalk’s bounty campaigns it’s just user’s posts. I agree that it would be good idea if bounty threads could be published only by trusted bounty managers it could prevent many users from dishonest people but it won’t be easay and it’s not a priority of administrators.
Everybody knows bitcointalk accounts can be bought (this is not yet forbidden although I think it should be) so you shouldn't base your trust in other user only on his rank.
But you can always spend some time to make some research and check if this "Legendary" user has positive trust,  feedback from other users etc... It could reduce the risk but you must always stay alert..