I’m aware that the Entente was essentially compelled to add the clause if they wished to justify their reparation claims, but I’m unsure as to why Germany and even (at a later date) Wilson and George would have passed doubt as to Germany’s guilt? Germany literally began the hostilities. Why was there such outrage at the clause after the war amidst the population whereas there was very little in either Austria or Hungary?
It wasn't just about whether Germany started it, it's a bit more than that. If anyone else would like to address the German reaction to the Treaty of Versailles, please feel free to type up your own answer! More insight is always welcome from anyone with the knowledge to contribute. While we wait for new material, OP, this thread from last month has u/Kochevnik81 and u/Starwarsnerd222 looking at the Treaty itself and the German reaction to it.