I wouldn't expect it to be less murderous than the aliens themselves. That wasn't my point at all. I'd expect it to contain all their knowledge and be able to live "forever".
But I generally wouldn't expect aliens to be "murderous" at all. Why send a group or probe lightyears away just to kill or enslave a primitive species? If they have the ability to do that, we wouldn't really have anything of interest for them.
> Why send a group or probe lightyears away just to kill or enslave a primitive species?
Killing/enslavement just as a side effect. You have to tell it explicitly to NOT kill/enslave covering any edge cases. Even if they do we can turn out to be sufficiently different that the probe doesn't consider us relevant from aliens' standpoint.
> Why send a group or probe lightyears away just to kill or enslave a primitive species?
That question makes no sense. It presumes that they are at all interested in, or even notice, us. We're special, from our PoV. That doesn't mean we are special.
Did you notice how many ants you drove over on your last car trip? Did you even care?
To a space-faring species, we are probably just as interesting as ants. After all, you are assuming that they'll send their brightest minds to visit us, but it is equally likely that we are "discovered" by their equivalent of joy-riding teens.
At most points in time resources are scarce and not all life can be supported. At those times beings with a tendency to say “them” will give way to beings who most strongly assert “us”.