I disagree with Tim Walz on this one - and i'll explain my reasoning. You've highlighted many genocides and those are often as a result of a one-sided war, though you did miss the Rape of Nanking. More often than not, a genocide is couched in terms of a just war for some reason and remains 'war-like' in its appearance - that is, people are kidnapped by soldiers and shot, or bombed by another nation state. Sometimes that can be supplemented by a civilian uprising - as happened in Rwanda in the 1990s AND perhaps crucially, in the early stages of WWII as the Germans co-opted the Balkan states and much of Eastern Europe.

Had that remained the modus operandi, I would agree there was nothing which makes the holocaust a unique event. However, that isn't where it stopped. What I think makes the Holocaust unique is that there was a dedicated infrastructure, mechanised like an abattoir with which the Germans were systematically collecting and wiping out individuals. It is the industrialisation of the process which sets the matter apart from other genocides and (to my knowledge) hasn't been replicated since.

There is an argument, which i think you and Tim Walz are likely making which is, does it matter if lots of people end up dead - to which the pragmatic response might be 'I suppose not'..... but I would still argue a moral difference and one which requires more careful scrutiny before it is dismissed. :o)