Saw this episode when I was relatively new to anime and even now after having gone through hundreds of more titles, nothing has really come close to reaching the same level of highs for me.
In addition to what others have mentioned, I think if you ask for sources they're basing their opinions on and point out objective problems with them and associate them with the US media's atrocity propaganda track record, I don't really see how it can be seen as anything other than being about media literacy rather than holocaust denial.
Some sources that I think should cover most of the problematic narratives surrounding the issue copied from my response in this thread https://hexbear.net/post/39756
Debunking stuff/illustrating the widespread problematic reporting surrounding this issue:
What is (most likely) actually going on:
@Yun
@hexbear.net