This isn't too big to fail, it's "a bad egg doesn't ruin the bunch." Whether that's the case here is arguable, but no one is saying they aren't responsible for their actions.
Is 'allowing for variance' up to and including racism and sexisism in hiring? Because it seems like you are giving them a pass, because there are many hiring managers.
If someone who worked for Walmart became a murderer, would you condemn all of Walmart as murderers? Promoting a culture of murder?
If that's too far removed from the actual job for you, how about if someone at Walmart acted in a sexist way in an interview. Would you condemn all of Walmart? Would you automatically assume there is a culture of sexism? Or would you at least entertain the possibility that Walmart employs thousands of managers, so it's not crazy to imagine that some of them might sometimes act in sexist ways, even without such a corporate culture?
You need more than a few instances to prove a claim of "this must be a cultural thing", IMO.
A Walmart shop could be an isolated environment where a bad person can prosper despite a generally contrary company culture, but it isn't an appropriate comparison for this case: important HR managers like this Alogna aren't many, even in a large company, and the higher level management who kept him and fired the recruiter is an even smaller part of Google. They must be assumed to be representative of the whole company.
I'm not saying that bad behavior should be dismissed. But I am saying that the larger the organization, the more potential there is for there to be a bad actor that doesn't match the overall organization's culture.
If the recruiter's accusation is indeed true, then we should ask questions about whether it is endemic to the entire organization. Though given the company's size—especially its growth through acquisitions (such as YouTube)—it's likely that the behavior is constrained to a single manager or department.