I do greatly appreciate you talking about cases instead of leaving it at saying there isn't a part of the license and calling any discussion about it FUD.

The Cisco case was about distributing GPL binaries, not linking it with the rest of the code base and the rest of that code base then needing to be GPL. It's a standard license enforcement unrelated to the unique requirements of GPL.

The BusyBox case is probably the closest in the list, but as you already point out we didn't get a ruling to set precedent and instead got a settlement. It seems obvious what the ruling would be (to me at least), but settlement was explicitly not what is being talked about.

Bringing in French courts, they issued fines - they didn't issue the type of order this article talks about which is about releasing the entire thing involved at the time with GPL.

This isn't related to fear, uncertainty, or doubt about GPL. It's related to what has/hasn't already been ruled in the court systems handling this license before as the article skips past a bit. Even in the case we assume the courts will rule with what seems obvious (to me at least), it has a tangible difference in how these cases will be run, the assumptions they will have, and how long they will last.

TBC, I'm not talking about the article, which I've barely read but looks rather misguided as it seems to be talking about LLMs having to be GPLed because of training data, which is not something that would ever happen.

It has never been the case that including GPL code in your software automatically makes your software GPL or even requires you to make it GPL. If you do get sued because you are distributing GPL code in a way that colloquially "violates the GPL" (technically, rather, in way that is not covered by the GPL or by fair use or any other licence, so it violates copyright) you might choose to GPL your code as a way of coming into compliance, but doing so is neither the only way to achieve compliance (you can instead remove the GPL code, and companies with significant investments in their proprietary code typically do that), nor does it remedy the harm done by your copyright violation to date, which you will typically have to remedy financially, via damages or a settlement.

As for legally testing, you seem to be to wanting a court to explicitly adjudicate something so obvious that in well over 20 years of FSF enforcement no company has been daft enough to try and argue in court.

It might help if you try and delineate exactly what sort of case you'd accept as proof of "enforceability" of "virality". I think it would have to be something like a company embedding GPL code in proprietary code and then trying to argue in court that doing so is explicitly permitted by the GPL, and sticking to their guns all the way to a verdict against them. I'm not sure whether that argument would be considered frivolous enough to get the lawyers involved censured, but I certainly doubt a judge would be impressed.