Agreed. The body count argument is a pretty insensitive (and very ineffective) line to use if you're pro-life.
However, I think a legitimate parallel could be drawn from the fact that much of the Holocaust was driven by German(ish) people who believed they were were dealing with a sub-human race. In other words, they did not believe the Jews had a similar right to life as they had. It was more than just a hate or power driven tragedy.