On one hand, this is a very, very bad bug. On the other, the article is almost of hit job to try to prove FOSS would have solved this issue. There are also a lot of completely factually incorrect statements and wild assumptions.
If my understanding is correct, the device in question, the Freestyle Libre 3, is the most popular continuous glucose monitor (GCM) in production. And, one of only a few approved GCMs available. By the very nature of being an extremely popular device that helps manage a chronic, high effort disease (diabetes management is a massive, massive mental drain) - you're going to have failures.
Not to mention, I've always been under the impression that GCMs have some faults and IF the device reports do not match your expectations, you should confirm with an alternative method (like a finger prick) or seek emergency medical attention (which should have been sought in these extreme circumstances, anyways).
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Here's the thing for me. FOSS essentially assumes that the user is going to be willing to understand the underlying details to know when FOSS fucks up. Yes, when FOSS fucks up. That's simply not realistic for any consumer product. If your argument for FOSS relies on users being able to read raw data and interpret things that are only learned by education, that's not a consumer grade solution.
Anecdotally, I used use Abbott's Lingo CGM a few months ago to help get me more data on a health issue I was having. I would never, ever, in my wildest dreams have trusted FOSS to get this right. There's simply too much money/effort/rigor involved in getting these biomedical devices correct to believe that the FOSS community could simply create a better product without actually doing any trials or studies. Not to mention, the recommended app (Juggluco) has a terrible UI. This just isn't going anywhere.
To be clear, this is a deadly bug and Abbott should be held accountable - but claiming the solution is some untested, untrailed, terrible UX is not the answer.