The 98% seems a rather high percentage, because there is a high probability that such a highly sociopathic species would not survive the invention of weapons of mass destruction, at least not as an industrial civilization.
Oh I mean that most species would do it those not like them. They'd curb their own impulses among themselves (or not have any, though divisiveness within your own species is ultimately a survival trait).
But they would have extreme difficulty not doing this to another species, especially if the other species was similarly xenophobic.
That's where humans and these other species come in. They're willing to take the time to adapt and speak with these kinds of species, perhaps using robots as intermediaries, or adopting their cultures as much as they can, and similar things. The various species would tolerate humans (or whomever) because they'd be willing to bend over backwards to be good neighbors. These species would then use humans as intermediaries to deal with the other extreme xenophobe species.
Obviously a large number of humans would be xenophobic as well, but by and large humans would be less xenophobic and have a higher percentage of those willing to try and understand, something that doesn't exist in the other 98% of species.