It's impossible, at this time, to really know with a degree of certainty. But my intuition (take it for what it is) tells me that some forms of ethics are mostly universal.
I am sure we are free to destroy our own civilization and even our own biosphere. But going after another civilization like that, or even destroying a biosphere like some want to do to the potential Martian biosphere, would put us on a probation of sorts.
I don't claim to know the answers or possess any hidden knowledge. It just seems to me this behavior is as universally despised as many ethical principles are universal to humanity.
There probably are civilizations out there who don't care about it, just as we have our own political factions who have abandoned human morality. But I doubt they are the rule and I doubt we will encounter a civilization like that anytime soon.
Earth really is located very far from likely locations of civilizations that span entire star systems. For that you need a star cluster. We don't live in a star cluster. We are sitting out here in isolation.