First we need to make the assumption, and it's a big one, that there are races out there that are both intelligent AND have a means of traversing interstellar space in reasonable times.

That puts us at a pretty low risk, but Brin is right to point out that there is nothing at all to indicate that advanced technology and intelligence go hand-in-hand (or whatever-in-whatever) with benevolence toward other races.

In fact, the biological imperative of evolution would tend to indicate the reverse. For any species, another species using the same resources is an enemy.

Intelligence is a freak of nature. An intelligent species can actually prosper by learning from the "outsider" (imagine how evolution might work if a lion could learn how to run faster from an antelope, or how to camouflage itself in the grass with stripes from the tiger.) An intelligence species thrives on diversity and "the different."

But that biological xenophobia is still under there. We fight it every day ourselves, often unsuccessfully, and I see no reason to expect that another intelligent species would be any holier than we are.