That always struck me as a pointless notion - I doubt an aggressive alien species would be able to reach the level of shear technological power needed for viable interstellar travel, without first destroying itself.
Plus, it’s unlikely we’d have anything to offer that wouldn’t be “economically” easier to find closer to their own system.
Based on what happened on Earth, to evolve advanced intelligence faster than asteroids reset life probably requires a war making disposition. We killed off all our serious competition, so a second rule is only one advanced intelligence life form survives in a domain, such as one Earth or one galaxy. If we are not alone the odds are humans will be killed off as as competitive nuisance. We should keep quiet. This is the best guess based on what we know about the millions of life forms that had their day on Earth.
They may want our water, which we cant seem to find anywhere yet...
I don’t think that we can depend on aggressiveness culling itself out. As long as aggression can be kept outward and not inward it can survive and controlled aggression is a survival trait.
For example lets imagine a species with an extremely xenophobic nature. They can be perfectly passive and cooperative with what they see as part of themselves but utterly ruthless to something unlike themselves.
Or what if a intelligent, highly developed, but passive species were to interact with a less developed but aggressive species? Imagine western liberals dealing with Muslim extremists if you will. Before the passive species knew what was happening, the aggressive species could be destroy them with their own technology and outrun their own destructive tendencies enough to find other victim species to exercise their aggressiveness.
Personally I think it is pretty well us, the angels and the demons, but I’m prepared to be wrong. In any case, if there is anything that might hear us we should probably not be shouting out location because the response is probably more dangerous than we can imagine.
Until we know better about what is out there, we should keep our heads down, mouths shut, listen and learn. Remember the old saw: “We learn more by listening than talking.”