That's a different legal problem as there are situations where if you don't protect your trademark you can lose it. But I'm not a lawyer and don't know if that situation would apply to mods.
More importantly, are they a lifeforms that we would even recognize as alive? The chances of an alien being humanoid are even slimmer. Then there's whether they develop intelligence, whether they care about space, and whether they survive long enough to get anywhere.
Looking for closure?