There is a trait in the Jewish character that does provoke animosity, maybe it’s a kind of generosity towards non-Jews. I mean, there’s always a reason why anti-anything crops up anywhere; even a stinker like Hitler didn’t just pick on them for no reason. I mean, if you and I were in a line moving towards what we knew were gas chambers, I’d rather have a go at taking one of the guards with me; but they (the Jews) were always submissive.
He clearly didn't understand the actual history of the holocaust and gas chambers, as many of them didn't know they were going towards gas chambers, they were told they were 'showers', and many people were killed besides jews. Also, yes, there are reasons a lot of people have been against jews throughout history, but that doesn't mean they were all good reasons, and none were reasons that merits killing jews.
Even if his quote was historically accurate, it would still be abhorrent. And if you pointed out his mistakes, he wouldn't have reconsidered his views. He didn't hate Jewish people because he incorrectly thought they were cowards, he incorrectly thought they were cowards because he hated them.
none were reasons that merits killing jews
Yes, because there is no reason that merits killing anyone based on their ethnicity.