> and don't go spewing their shit all over the cosmos

Why? What's the downside to littering on some random asteroid? There's no ecosystem that would care – not even bacteria – nothing and nobody would mind if you drop a plastic bag on 423 Diotima. Take a step back and think about why pollution on Earth is bad, and you'll realize that "polluting" an asteroid isn't ethically wrong.

Of course, that only applies as long as those asteroids are utterly devoid of life. Once there's an ecosystem, polluting becomes ethically wrong again.