oro can turn out to be slimy snake if he goes their and changes sides.he probably is saying that he is supporting the four hokage so that he can save his ass coz first who is not under his control can kill him then and there.But if he goes their and then changes side then he will be under madara's protection. Thus if he goes and changes side then it will be a though one coz it WILL BE
HASHIRAMA,NARUTO,SASUKE(juggo,karin and the water guy too as they support sasuke) AND THE SHINOBI ALLIANCE
VS
MADARA,OBITO,JUUBI(made powerful with help of nine talis chakra in minato probably)THE 2,3&4 HOKAGE AND ORO
talk about a one sided battle
HASHIRAMA,NARUTO,SASUKE(juggo,karin and the water guy too as they support sasuke) AND THE SHINOBI ALLIANCE
VS
MADARA,OBITO,JUUBI(made powerful with help of nine talis chakra in minato probably)THE 2,3&4 HOKAGE AND ORO
talk about a one sided battle