Presumably they're involved because they have a number of APIs, and they believe that APIs should be copyrightable. I don't think they would take a position on this issue due to an opposition to Google alone.
I agree that we can't infer their true beliefs (to the extent it even makes sense to talk about a corporation's beliefs), but I think the position that APIs should be subject to copyright is actually reasonable (though IANAL).
Minor correction: they believe it's in their best interests that APIs should be copyrightable.