This was the last straw? It's fucking awful and he's a piece of shit for it, but this is far from the first indication of him being an unforgivable piece of shit.
That people have to literally dawn a swastika in support of nazism for people to recognize that they are garbage human beings is fucked up. At least literal nazis can still be seen as bad...
I think we can see from the reaction to the hitler salute, that cognitive dissonance (or flat out support for nazism) is a hell of a drug, and will produce an endless stream of excuses and justifications to avoid acknowledging/admitting the truth.