He wasn’t charged for slandering. We have a specific law for denying or playing down the Holocaust and other Nazi crimes.
How about a specific law for denying Armenian genocide? How about a law for denying commie crimes (GULag, Holodomor, purges, Great Leap Forward etc.)? How about a law for denying or playing down the German crimes during WW II? Where do we draw the line? This is slippery slope. I find the idea of putting anybody to prison for EXPRESSING AN OPINION (even though it may be a stupid opinion, but so what - liberals are also stupid and we don't put them to jail for that now do we?) to be totally incomprehensible in a civilized society.