well, I see your point, but kabuto sure knows that it isn't real naruto, so, why would he want raikage to hold jsa, also, it isn't all jsa, it is just a part, other parts are on their way.kabuto has been talking about his trump card very much recently, so, I think "him"is the 6th coffin .Also, we know, madara six paths have rinnegan sharingan, but in the end of day, they are still edo summonings, so when, kabuto's edo jutsu breaks, they are going to disperse as well.so, they aren't great threat at all.even if madara use rinnegan on their dead bodies, they won't be able to use their bizzu powers.
I get it!.... I know who kabuto is referring to stall time for him.he summoned muu back so that he could hold itachi and buy some time for kabuto to summon 6th coffin.kabuto must know the position of his edo, so, he know itachi is on his way to kabuto.