I personally believe any intelligent aliens who exist, whether on Europa or elsewhere, could easily choose to hide themselves.
After all, if any aliens either observed our TV signals or observed human behavior on Earth, they would know as a species we are a long way from overcoming our innate tribal hatred and hostility for anyone who is Other, even if that's separated by religious beliefs that are very little different (Ireland). Let alone huge areas of the planet that have constant ongoing hostility (the Middle East). And certainly any human who looks markedly differently than others (i.e. different races) is treated profoundly differently.
If they are advanced enough technologically to visit Earth, the odds are our weapons would be no threat to them. If so, they clearly are not conquest-oriented, or the "war" would go faster than Bambi vs Godzilla (with us being Bambi).
Therefore, I assume they are hiding themselves, not out of fear, but because they don't want our civilization to self-destruct itself in a "war" against vastly superior technology. And if we didn't, our civilization would still implode from the profound shock waves that finding intelligent other-worldly life would bring, from economic to religious and political chaos.
So, I hope we don't find intelligent life on other planets until we, as a civilization and species, are truly ready for the shock. If anything, I think sci-fi helps this tremendously by introducing people to the idea of other-worldly intelligence and perhaps on some level preparing them for an eventual friendly meeting.