So, are the Caucasian people who were involved in any of these miss-optimizations, aka mistakes, racist against themselves? Are they traitors?

"I want a model that produces racially diverse images of people, but I didn't test it in racially homogenous historical contexts" => yes-racism, according to you.

You are again misrepresenting the OP. If you go actually read the OP you will find it very clearly describes Google's initial steps towards fixing the problem, which was: double down on race-swapping in historical contexts. The OP very clearly (and correctly) argues that this is not the action of a person who goes "oops forgot to test in this context" but is rather the action of a person who very intentionally wanted the image generator to behave this way in this context.

But probably not simple enough to pierce ideological bias. I'll ask instead: you really believe that it wasn't tested in historical and other contexts where white people were erased?

Occam's Razor: Of course it wasn't or they wouldn't have released such a ridiculous embarrassing product! C'mon, I think you're the one wearing blinders here.

Of a piece with 'Google more or less explicitly said I won't be promoted because I'm White' stories.

Then please do explain why their first reaction was to double down on "diversity" in historical contexts, before eventually retreating?

Have you never tried tweaking the error text first before giving up and redesigning your form that's confusing users?