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.

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”.