Just post the testimony where he denies "any gassings". You're going to get shredded here. Morgen was not a friend or defender of the regime. At best you can just say he was forced or cajoled into saying things by 'powers', just like all the rest. Denial. no way.
Don't recall if he did or not. Do recall getting taken to school by Nick about him saying there was a gas chamber at Buchenwald. He didn't. I thought he did, but, he didn't.