I call BS on premise of that link, and on the original essay (which is now online: http://peachfront.diaryland.com/enderhitlte.html)

Claims like this fail the Occam's Razor test:

I've seen Elaine's notes and heard Card on the phone, and there is no doubt in my mind that the Hitler Hypothesis is correct; it is simply impossible that Ender's Game and Speaker were written by someone who did not have a very detailed knowledge of Adolph Hitler's life. There are very exact parallels in there that you wouldn't even notice unless you read the footnotes to the most detailed Hitler biographies. I also tend to believe that Card does not have that level of knowledge about Hitler.

It would be simpler to assume that a story where a person causes the extinction of a species would have some similarities with a war in which genocide occurred.

I've read Card's books and I have reasonable knowledge of Hitler and I didn't notice any particular parallel. I suspect that the claim that he doesn't know his own books comes more from a reluctance to engage in a telephone debate rather than the idea that he didn't write them

I say that as someone who really liked Ender's Game, but thought Speaker for the Dead was crap. I had always assumed that Speaker for the Dead had some kind of Mormon message, but I think these accusations go way too far and are unsupported by the evidence.