Wait, who said the ending of The Road was happy but bittersweet? It's totally ambiguous ... it's end with blind faith that could swing either way. I'm trying not to spoil things here, but man that ending I felt could be seen as a devastating mistake or a chance worth taking.
Also I know the writers of the game tried to make it clear the surgery was the only solution, but when has science that experimental been 100% accurate? They're trying to cure a deadly, highly contagious disease... I don't care how many journals and recordings they leave around any reasonable person would have to assume this is not guaranteed to work and that patient should be told of what is about to happen.