Yep, the best thing for a race that is (rightfully) worried about our aggressiveness is to wait it out.

It's more complicated than that.

Benevolent aliens are planting incompetent people in positions of power so that we are perpetually on the verge of self-annihilation. But this is all to save us from the malevolent aliens who would obliterate us if they thought we had any chance of survival.

Or launch an attack fleet, only to later, due to an error in a scaling factor, have the entire fleet unknowingly swallowed by a small dog.