I don't find it hard to be suspicious of this paradise being presented. The issue of energy really is the key here. You'd assume the Reiji Maigo, but if that was the key then Yuji wouldn't be so for it since he could hardly live with Shana in their world then. He'd either have to leave it and disappear or keep it and the plan wouldn't work. I do think it'd be a more interesting moral debate if just copying the world did copy everyone in it. Give the Tomogara human 'copies' to use as livestock of existence.
Besides anyone who turns a won battle into a full out massacre....
Maybe they have all these episodes now to figure out what is the evil catch behind the plan
.