The thing that always bothered me about this example is Panda's can't shoot guns. So there is never going to be a person who reads that sentence (provided we are not talking about an anthropomorphic panda), and misreads A as B. Also that sentence without the Oxford comma is "The panda eats, shoots and leaves", so even if it is an anthropomorphic panda, there isn't much ambiguity in the sentence without the oxford comma. My feeling is if people want to use the oxford comma in every instance, they are free to do so. I think there is a better argument to be made to use it when it helps avoid ambiguity when context doesn't make the meaning clear (but I also have to admit, I like ambiguity in writing).