True. There is mention of Holocaust survivors who made it over the Urals speaking out on TV, though... and then the nice, clean-cut German diplomats come on to deny their 'crazy' stories. (One of the more stomach-turning scenes in the book, IMO.) So, there's some awareness of the concept. Enough for Charlie's evidence to decide the outcome of a close election, perhaps.
Perhaps, but then again, it as hard for people in immediate post war years to actually wrap their minds around the idea that this could have happened. and that was with thousands of survivors, actual camps being liberated and Gemran losing the war. TTL has none of that so documents are just as likely to be dismissed as forgeries and made up by communists and/or people opposed to detante. And if not the question is how many Americans would actually care. Remember, there is no Israel (i lobby) to bring up Holocaust when needed.