Mars is in a solar system occupied by an indigenous conscious species - meaning, it belongs to this species.
If Alpha Centaui belonged to aliens and we settled it then YES, they have the legal right to evict us if they 'feel like it'.
And if the eviction of 600 human colonists from Alpha Centauri would help BILLIONS, then YES, they most definitely have the moral right to evict us from there.
As for 'blow Mars' - that's just your attempt at a straw-man.
So you 'own' your own solar system but aren't allowed to establish any other colonies in the Alpha Quadrant unless you join the Federation, Romulan, Klingon or maybe Cardassian Empires.
What if Earth.Gorn/Organian/Halkan don't agree to this division of the galaxy?