Bleh, I think the Zerg are cute and/or cool anyway, I don't know why PETA is selling them short.
Okay, so, I'm working off the idea that the Zerg are all about consuming compatible essences (read: other Zerg) and the assumption that they're all at least as smart as your average... I don't know, raven, maybe. Based on these two assumptions, I would conclude that the Zerg would figure out pretty soon that humans aren't really their prey of choice. SO, working off THAT assumption, I can believe that, as long as I don't go out of my way to antagonize a Zerg, I'll be able to get along with them.
Also, if they could merge with certain Earth creatures... Kitty Zerg! Do want!
Oh, and we can make like Dr. Egon Stetmann and study them until we can improve out stuff and people with Zerg properties. VERY cool