There are 3 axes of risk: probability that something goes wrong, the impact of something going wrong and the time to remediation when something goes wrong.
You're arguing that on shoring QA would reduce the probability of something going wrong. I'm neither going to agree nor disagree.
However, I think the failure here is to mitigate the impact of something going wrong. Their rollout plan was fundamentally flawed - it shouldn't have taken out so many machines at the same time. It should have been rolled out in stages, with only 1 machine at most at any given customer receiving early versions.
It's best to assume a bug will get through 1 day or another, and spend some time mitigating the other axes too.