A reason for the twist

Don’t get too angry, though – this isn’t just a twist for the sake of shock and it doesn’t mean at all (just yet) that Lex can be a physical threat. It just means that there is a reason why such a young Jr. is the leader of a tech behemoth company.
And, in this way, this twist doesn’t undermine the whole idea of Lex Luthor, the man who made it on its own and who challenged the gods. From a physical point of view, he is still scrawny. He just happened to inherit the means of creating and developing technology ahead of its time.
This also explains how he was able to manipulate genetically the corpse of Zod and transform it into Doomsday. First he needed a way to penetrate the impenetrable skin, then he needed the knowledge to actually break down the Kryptonian genetic code and tamper with it – as far as we know, Jr. might just be the descendent of a brilliant scientist.
The rivalry between him and Superman is also explained at this point. If traditionally the battle is between man and god, now it becomes something else – the battle between the one supposed to inherit the world and his challenger. At a certain degree, it is like a battle between brothers. And this is something we have seen before – so, in a way, might please some fans.
