I saw the significance of it, but thought that people would like to come up with their own puns on this easter egg (a second one is "Yumbo!" I've seen it, but fail to see what makes it so great). For one, they failed to create a new resource picture for it. It, if you actually placed it on the map, would look just like the furs do. If I'm not mistaken, this is either a ferret or a mink, much too large to be a Guinea pig.
On second thought, this might not be too funny of an easter egg. I just thought that it was funny that they put it under strategic and wanted people to come up with their own ideas on why he's so rare and elusive. For one, this could be a "killer Guinea pig" that has been unrecorded by history and led to the destruction of the natives after the Europeans came. It's sweet looking like the "killer rabbit", but beware! It hates sunlight and so you never see it. It, however, attacks anyone who comes too close.
It's not necessarily the best idea, but it'll do for now. What about his demise? What led to it? Did it really ever happen at all, or is this just an illusion?