That's because Jason is not Superman's son, we were just lead to believe he is...We saw what Singer wanted us to see...for a reason. Superman believes Jason is his son. Lois believes it. But is this reality? We don't know. How is this going to play out in the sequel? Didn't superman seem to come out of his loneliness when she found out Jason was his son? Wouldn't it be even more tragic if he finds out that he is not. What if Supes finds out in the sequel that he can't have children of his own. But, just think that if Richard does die and Superman steps up to marry Lois. He then adopts Jason as his own. That sounds like a hero to me.
I just don't think that WB, who has protected Superman's image for so long, would let Superman be seen as a dead-beat dad. But if Singer came to them with a vision, a game plan for this kid all along, I could see how they'd go for it.
Imagine a scene in the sequel, much like the end of The Usual Suspects, in which Lois swears she saw Jason throw the piano at that guy and the scene replays, this time from a different angle...there was a struggle, she was on the floor...behind the desk...the ship lurches and the piano (was it on rollers?) comes crashing at the crook..what did she really see?
Again, I could be wrong. Look at what they (DC) did to Blue Beetle - shot that poor bastich in the head. Perhaps they are looking to truly add a Superkid to the Superman family of characters. Either way, Superkid or not, it creates great drama for this new franchise and I'll be in line for part 2. I want to see it now.