Life outside the solar system can be proven or disproven.
Disproving life outside the solar system is technically possible, but completely unfeasible. You'd have to search the entire universe. Saying that makes it scientific would be no different than me saying God is on another planet, we just haven't been to it yet.
But how would you disprove God? Disproving life outside of the solar system (can we just say Earth?) is possible, as you noted. But can you devise a test to disprove God? Unless I'm wrong, that's one of the reasons God is not scientific: No test can be devised to disprove it's existence.
can't be proven or disproven. Which is why it's not scientific.
Well done.
We can currently prove ET life exists just as much as we can prove god exists: we can't. Unless you were planning on taking your Prius to go look.
God can't be disproved. No test can be devised that God can't simply fool. Heck, God could change the rules of reality. How do you use science against that kind of supernatural power?
And as Rushy pointed out, life outside of the solar system CAN be disproved. It's impractical and not worth doing, but it could be done.
So, God is not the same as ET. God can't be disproved, ET can.