Let’s trade positions with a prospective alien race potentially visiting Earth. Let’s say alien contact never happens, and humanity is forced to progress technologically by itself until it reaches a point where travel through the cosmos is possible. The painfully simple truth about alien contact is that an alien (or human) leader would face a daunting task when reaching a new planet and deciding whether or not to make contact with the species below.
It’s strange to see in Star Trek or any number of other shows that often a primitive alien race is not the least bit interested in the technology aboard the Enterprise or being carried by those visiting their planet. Say we were to crash one of our ships on the planet’s surface accidentally, or be forced to shoot down a rogue ship onto an alien planet and note the curious natives taking apart the vessel and learning how to use it. We would be faced with an ethical quandary. Do we take back the ship? Try to make contact? Or simply let the natives continue to study technology centuries ahead of their current capability?
Whether or not there is an interplanetary protocol for contact, no doubt there would be an entire chapter set aside for military generals who want alien technology and the coordinates of their home planets. Yes and no isn’t an option as the technology likely would make discovering such a planet quite easy. No and no would be difficult as there is a very real possibility the developing race would remember such rejection and hold a grudge once it made it to the stars.
And a grudge with humans would be of particular danger to an alien race when you consider a potential technological plateau. At some point, technology may reach such an advanced degree that it simply cannot get any more advanced, or a species may find no need to continue to advance as all of its needs are taken care of. And if all needs are taken care of, then there would be little to no justification for weapons of war. The human race, scorned by the extraterrestrial visitors may then discover their homeworld carrying with them great weapons capable of destroying everything in their path. Of course this is purely speculation and seems unlikely to us, but may be compelling enough an idea to leave the human race alone entirely. Furthermore, it is not the length of time an alien race would have had such advanced technology that would be an advantage. Humans, having only recently come out of a very warlike way of life, still carrying with us a lust for violence and conquest may prove more dangerous than an alien race that has become complacent and peaceful over the course of thousands of years. Would this alone be enough reason to raise suspicion?
If an alien race asked for our technology and coordinates to our homeworld, we may find it dangerous to comply without integrating our two species together first culturally. And with the fear of change and difference so many of us have, would it even be possible to do this? Perhaps it would be more wise to experiment with alien reactions to human presence first by picking a few of them up at a time and dropping them back on the planet with no memory of the experience.