My impression, as to why Rachel chose to make Dr. Hamilton and not Dr. Klein Superman's doctor, is that Rachel is strongly influenced by Superman in other media. In the comics there is no Dr. Klein, but Dr. Hamilton used to figure prominently, at least for a while.
I'll be back with more feedback later. (Although, about the rating of the story... being a Swede, I had no idea what either T or M stood for, but I guess these letters refer to teenagers and mature readers. As a 13- or a 14-year-old, I myself would have been devastated by the violence in this story.... but that was back in the sixties, half a lifetime ago.)
Ann