NASA has this "planetary protection" scheme. But it seems to apply to non-planets, like Enceladus and Europa. Thus Galileo and Cassini probes are crashed into their gas giants. How does this add up? Is there a misnamed everything-in-space-"protection" policy?
"Planetary protection" is a minor misnomer. From NASA:
Planetary protection is the term given to the practice of protecting solar system bodies (i.e., planets, moons, comets, and asteroids)
"Planetary" is simply an easier word to manage than "celestial-body-related".
Such misnomers are extremely common in all fields.
The term "planetary protection" predates our current understanding of our solar system. Since 1958, we've made discoveries that led scientists to consider the possibility of life existing on moons like Europa.
So the responsibilities of the Office of Planetary Protection expanded, but the name stayed the same.
Planets, moons, comets it does not really matter. The goal is to protect an environment where life could have developed or might develop. The name may not be entirely well chosen for accuracy as opposed to emotional impact.