Tell me what there is to argue here...If anything his argument is a nothing but a fallacy, obito is not doing this for the shinobi, he despises the shinobi system, he's doing this for the world. He doesnt care how many shinobi die, the more the merrier in his mind because that's one less person who has to potential to spread the hatred which he is trying to stop.
The shinobi are merely in his way, they are obstacles to him. His goal revolves around eradicating all shinobi from the world anyways, why does it matter if he kills more shinobi?
Another point, he refers to this world as the "fake" world, nothing in the physical world has any meaning to him anymore, the people are of no meaning either. The only people who hold any real value to him are the ones who are created inside the genjutsu.
His goal is to give the world a better dream, no more murders, no more wars, no more chakra or ninjutsu. Utter bliss in a utopia, the shinobi who want to ruin that will be killed, simple. U_U