Alright, it looks like most of the talking has died down here, but I would like to make a few points.
1. He has a RIGHT to make this game, so stop complaining!
This is what I like to call technically true, but also not always. For instance, you can right now go to a synagouge and say that you think the holocaust never happened, Jews steal people's money, and any other number of terrible things. That is your right, but we as a society have made rules saying it isn't right.
For example, Westboro Baptist Church has the right to protest, but society as a whole has come down hard on them. That is why people counter protest them. The argument of "He has a right to make this game so STFU!" is flawed. It is saying that since he has the right he is free to do whatever he wants. That isn't true, because we on the side thinking this game is bad can air our issues with it being made.
2. Other games are like it, this just has different models/context!
Context, my friend, matters. Let me use a very easy example, pornography. RapeLay became famous because it allowed you to rape young women and enslave them, but that doesn't make it too bad compared to some other games. What set it above the rest was that you could rape obviously too young children, crossing into child porn. Though it was not actual child pornography it was still attempting to imitate the look.
What more, what if the "model" used for the game had been made to be even younger looking. Would that not change what type of pornography and whether or not it was right to be made? The model you uses, the context you put it in, changes everything. Context and the models can change a simple porn game into a child rape game. There is a world of difference despite the same game mechanics.
3. This won't hurt the game industry, it's just a mod.
Remember the Hot Coffee mod? Remember how you had to hack to get that one to work? Remember how Oblivion had nipples if you looked hard and modded the game? Remember how these two caused national controversies?
And do you remember how these incidents fueled California's violent video game law?
I understand your point, this is just a mod and won't be played by a large majority of gamers, and will most likely be played by a few thousand. That won't change the fact though that this will become an issue. Small things can become big, just look at the Oblivion fiasco. Sims even had to quell some issues when people released mods that showed the naughty bits. This makes the gaming community as a whole worse by being made.
Lastly though, I want to point something out. No one is honestly saying this man should be forced to not make this game. As I have said before, it is a right of his to make it. What this is is people saying, "You are crossing a line, stop." Much hate speech from Glenn Beck on Jews, Westboro on gays, and Nazi's marching through a Jewish community in Chicago we can not stop people from doing stupid hurtful things. We can however implore them stop doing those things and to join us back in proper civilization.