back it up without theorys pulled from left page im linkin u where naruto molds regular chakra using same stance here jiraiya tells him to mold his chakra http://www.mangapanda.com/93-149-15/...apter-144.html
and here naruto is shown using same pose http://www.mangapanda.com/93-149-16/...apter-144.html
as the kyuubi. have you ever thought that the stance is universal? there are two instances shown where they mold regular chakra and one stance where he molds sage chakra. so if you are correct why didnt kabuto and juugo use the same stance to gather natural energy?
keyword in your post u say Everything about them shows they use nature energy IMO... which is opinion i just countered u with fact.