A) this is a forum to express all ideas for naruto and the like so if he has a theory that you dont like dont read it simple enough.
B) we all know it cant be proven thats why its a THEORY this is just an idea trying to get people thoughts on the subject, IF we new everything about the charaters the anime would be a little dull dont you think lol.
C) good theory still a little doutfull, i dont think the so6p would talk about his own death the way he did but you never know.
D) what i think is more likley is tobi is madara like he said he is and the person in the coffin is the youngest son of the so6p or the sage himself thats who would scare him hell it could be orocimaru for all we know but there a lot of holes in this theory as well.