I don't find it over-emphasized. Many in the Twitter-sphere are acting as if they aren't being appreciative of open source software and I don't see it that way.

The technical root cause was in the open source library. There's a patch available and more likely than not OpenAI will continue to use the library.

Being overly sensitive to blame would be distracting to the technical issue at hand. It's great they are posting this post-mortem to raise awareness that the libraries you use can have bugs and to consider that risk when building systems.