My immediate reaction:
The primary function of the Zerg is to invade all planets around them that fosters life, enslave the animals with desirable qualities, aggressively mutate said animals to suit the needs of the Zerg and destroy all other life on that planet.
The Zerg inhabit just about every single possible quality that PETA loathes and fights! As cute as they may think they're being by launching this parody awareness campaign, they're missing the point so frigging hard by rooting for what I believe might be the only race that's worse than humans in treating other animals. You think us humans are despoiling this planet? Let's see what you think about the Zerg, after they're done sterilizing the Earth of all native life in a day or two.
Seriously PETA, just give up associating yourself with video games.