The idea that aliens that might potentially contact us are afraid to do so is just one of the thousands of “alien interaction” scenarios that science fiction authors have come up with down through the years. If aliens are only monitoring our audio and video signals (which have now reached as far as 80 light-years away) then if they can interpret them, they have seen that we tend to view contact with aliens as landing anywhere along a continuum from war to benign indifference to nearly messianic salvation from ourselves. If they have snuck in and gotten copies of our written works, they would have found far more scenarios of what contact with them could be like, from our perspective. There have even been many attempts to try to think like aliens, but those are still very much affected by our own biases. I like to think that eventually we will encounter aliens, some fanboy or other will realize “it’s just like X by Y”, and some other person will take advantage of that knowledge and make a fortune.
Come what may, sit back and enjoy this “travel alert” about us “dangerous humans”!