My statements on the matter of aliens stand.
It is highly statistically possible there are aliens out there in the universe, who are looking at all the others stars and planets in the universe and are having the same difficulties we are having in terms of interstellar travel.
In the event a civilization has managed to not destroy itself long enough to be able to traverse interstellar distances and survive the process, it would do so for a purpose. They either require 'real estate' upon which to grow their civilization, or resources to take back to their civilization, or are just exploring. The first two would be bad for us, but I expect there are other solar systems that are likely closer and more easily reached than ours so they are also of minimal chances of happening.
The third option, that they are explorers, would require a mindset of learning, which means interacting with their interests as little as possible and observe. To that end, they wouldn't want to deal with us because they would want to learn from us. Because we are not their equals (we can't travel interstellar distances), they would feel no need to associate with us, or make us aware of their presence, because whatever they can learn from us could be done by observation. The only purpose interaction may cause would be panic, envy, or adoration. For a scientific society, none of those three results would be desirable.