I had a long conversation with 3 people from Canon ... I can't say names, but this was at a national level, and included his boss from Japan.
I have even forwarded this conversation on to him, because it keeps coming up. You're right, it does look "fishy" that after this long, Wilhelm hasn't published their results.
The problem with Wilhelm is that while they are "independent" in one way, they are very dependent in another ... they need these companies to pay them pretty large amounts of money to stay in business. This situation isn't much better, and it is possible they have tried to leverage themselves to the point of holding companies hostage. According to my conversation, this is exactly where Canon is with Wilhelm ...
The simple fact is Canon's internal testing is more extensive than Wilhelm's, at this point even Wilhelm has admitted that worse case scenario they are at 95 years (and still going ... though I'm sure it's concluded by now).
My real problem with Wilhelm is they tend to focus only on the inks, yet the paper bases are a huge variable in how they react to ink.
The problem with longevity testing is it doesn't account for real world scenarios. I've also felt for some time that fading really isn't the challenge of longevity. Most prints will die from physical damage (lost, trashed, burned, spilled ... you name it) far before they ever have a chance to fade.
I'd be interested to know what inside information you have about Wilhelm's business to know that he has any capacity whatsoever to hold any of these companies "hostage" - hostage to what? They are his clients. They are paying for the tests and the data. Presumably they control what he is allowed to publish. Have you ever seen any of those contracts between Wilhelm and his clients to know who really controls what (I haven't, but I think I understand the basic principles at play here), or is this hostage business speculation on your part?
I think it would also be useful if you could tell us something about your background in the science of longevity testing and specifically what you know about Canon's methods compared with Wilhelm's methods to know that Canon's testing is more extensive than Wilhelm's, or are you just repeating back here what a few folks at Canon told you? I can understand if the detailed data wasn't allowed into the publid domain because, for example, there may be unresolved disagreements between Canon and Wilhelm about certain results, but that is a different matter and should be seen as a possibility that can arise in the normal course of implementing a contract.
Have you carefully read any of Wilhelm's reports on his website? You will see he not only focuses on the inks, but also on the papers. His tests include for yellowing, and they test for failure of the substrata. He has written extensively about both paper and ink. I don't understand how you could believe a scientist of that calibre and experience would not understand the importance of both, because if you and I know they work together, so does he - in spades.
Turning to your statement about accounting for "real world scenarios" - I don't know what that means, but whatever it means, it's irrelevant. Most of these tests are "accelerated light fading" tests. In order to get results out within our living lifetimes to be able to advise the manufacturers and their clients about the expected longevity of the materials, they can't pin the prints on fridge doors, leave them there for a 100 years and tell our grandchildren whether the prints lasted. I want to know within my life-time - in fact by the time the product hits the market. So acceleration is substituted for time, and therefore it cannot be "real-world" from the get-go, because in the real world you don't hang your prints in accelerated conditions. There is a problem with this methodology called "reciprocity failure", in the sense that acceleration does not necessarily correlate one-for-one with longevity, but Wilhelm is well aware of that issue too and his written about it.