Isn't it fair to say that anything with energy "broadcasts"? "Empty" outer space is filled with broadcast energies.
If the question is, as you stated, is it ethical to listen, I agree that is utterly asinine to ask.
If the question is, do aliens exist, this is a self-answering one: of course. I can absolutely name a known alien planet: Earth. It must be the height of hubris to think we are alone in an infinite universe, or even a somewhat smaller universe. Of course there's other lifeforms. Really, really smart ones too.
In fact, there's a historical log of contact; a long, extensive, well-documented catalog of encounters with non-earthlings. Many countries have had direct contact with aliens. We've filmed them, photographed them, tracked them on radar, seen them attend rocket launches, overpower military installations, fly over major cities, fly over the Capitol, appear in the skies of virtually every country on Earth.
Here is where I get flummoxed: experts, scientists, professionals, specialists, and a plethora of common folk have had direct experiences. Hundreds of thousands of them. Yet, there is a large group of intelligent people in denial that keep saying there's no proof. No matter how detailed, no matter how well-documented, no matter how many pictures and films and digital records are offered, they are still "unidentified" - mysteries in the sky.
This is a childish and destructive viewpoint. The sooner we accept that the overwhelming evidence makes it abundantly clear that we have been and are in continuous contact with alien species. There is no doubt. No doubt. As a species, we need to admit this, open this up to disclosure of the additional evidence, experience, interactions and materials of non-terrestrial origin.
Of course we're not alone; never have been. Perhaps it has something to do with the difficulty of the human brain to comprehend how immense the universe is; we cannot grasp it, it's theoretical, vague, incomprehensible. We simply don't have the brainpower to comprehend the distances. There’s room for more than we could, even collectively, imagine. The governments of the world are evolving their approaches, as are we, and sooner than later, we're all going to reach a consensus: that they're here already.
I've offered no specific evidence here because I wanted to use the space to state an overview. We've got the evidence, it's all right out there in the public arena, anyone can access it. Perhaps it's simply fear that keeps the truth from general verification; governments are coveting their own intelligence on aliens for political/military reasons; so we'll have to pry it out of their clenched fists; or we can simply wait for the public arrival of our fellow aliens, or we can keep pushing for full disclosures. Although there is the idea that the aliens are in charge, and they will decide when and where and how;perhaps we are already well along in their plans for disclosure. I cannot think of a more profound disclosure.