They know they won't win. They just want the attention and publicity. And like the article says, if they can garner any sympathy at all, and get a lot of press, this could pave the way for future advancements to fall in their favor. Or it goes along the lines of that old joke that if a kid asks for a pony enough times, her parents will be relieved when she switches to asking for a kitten and will gladly grant her wish (when, of course, all she wanted was a cat to begin with).
PETA people are extremists, and they're about the shock value, but the people in charge (and not the mindless masses of followers) really aren't stupid.