You can control the bounty manager to hide the email lists on spreadsheet yourself, you don't need to make post about it on here, I'm guessing that this happens almost every time when a new bounty managers tries to manage a new project, no reputable bounty manager will do such thing
Trust nobody, even bounty managers can engage in such act, for extra dollar more anybody can do anything, we are been asked to drop email address for unknown purposes, probably for marketing purposes who knows? But not all bounty managers can be trusted, anyways they are just emails, it's easier to create a new one if the old is full of spams