And here's the best thing - as long as that little bundle of sticks comes up to you in person and says 'holocause never happened xDDDD' as long as he avoids doing so "in a manner capable of disturbing the public peace" he is still legally able to do so even in Germany (or at least he doesn't explicitly break the specific laws against Holocaust denial). So yelling it in your face is probably not allowed but otherwise yay freedom of speech. It would probably be a stupid idea if he values his own existence, but freedom of speech wins again. Hurrah.
It's way out of proportion to say that it's a blanket ban on discussing or assessing the established history.
http://www.bbc.co.uk/news/world-us-canada-39575680
Melania Trump wins damages from Daily Mail over 'escort' allegation
The Daily Mail published allegations Mrs Trump "provided services beyond simply modelling"
The media does post any old garbage. But personal accusations without evidence are considered slander, go to court, and reward you with big $$$
Why should you be able to slander a country's-worth of people in a written publication when you wouldn't be allowed to slander a single person? Again, you can publish opinion but not 'slander'.
Even then, the holocaust denial does have some pretty thorough bases to base the opinions on, so it cant really be considered slander.
I wonder how suing for slander would work against any online paper, there are so many posting slander there that its just become an everyday thing. To the point where you just lose credibility in the paper posting that trash, and move on. The way it should work, no need to sue anyone.