we should not trust ANY alien tech - it'll just be a fucking bomb that we make for ourselves to annihilate our planet.

The aliens know when a race has 'nearly evolved' because a little white spot appears (briefly) upon their view of the cosmos, and they know another dumb race has 'built that thaaang'.

The really dangerous races (to the aliens) use the power of their minds to communicate with their local Star, activating the self-defensive stellar grid (the force) that protects all truly intelligent life in this Universe.