Yeah, but if you bought an Axe-FXlll (for example), you are authorized to use the includes IR/Cabs as you like, even combining them using a workaround or another, same thing with 3rd parties cab pack (using Cab-Lab...why not?)
"as you like" isn't how commercial copyright licenses work, they carefully specify how things can be used, they don't throw open the gate and then say "except…".
Even if someone hasn't read the actual laws, American copyright law is well understood by the public because everyone knows we don't steal from others, and any IP lawyer or someone who's familiar with copyright law will tell you that even if something isn't registered in the Library of Congress it's still copyrighted once its in fixed form, such as an IR. While we're not allowed to copy them, we are allowed to make derivative works, such as by using Cab-Lab. There is also the right to make an archival copy, but since they're already built into the firmware and it's trivial to reload them, that would satisfy that need and fulfill that right; I don't think an argument taking advantage of the backdoor to duplicate and extract the IRs "to archive" would hold water.
That users of Fractal's devices figured out they can duplicate an existing factory-supplied IR doesn't mean that Fractal condones it, instead I suspect FAS tolerates it because the general functionality and flexibility of the modeler requires that capability. Using that capability in a convoluted and nonintuitive backdoor way to gain access to the IRs could get shutdown if the vendors wanted to make an issue of it with Fractal, which they might if people suddenly started abusing that backdoor. As I see it, it exists because Fractal and the vendors prefer to be benevolent toward the users.
The third-party IR vendors understand how copyright works, and that it allows derivative works, but that doesn't mean that Fractal has to make it easier to get at the built-in IRs either. Fractal can choose to be more restrictive than the vendors, but they can't choose to be less restrictive than the vendors unless the vendors specifically say Fractal has that right. Unless the copyright is sold outright, it always remains with the original author who has absolute rights how it can be used. A licensee can't expand their rights just because "they like".
Discussing the issue with Cab-Lab on the forum won't do anything very useful since it's airing a complaint instead of seeking a working solution. We in the general populace do solutions here; Fractal people wander by but this isn't the official support, it's a social media site related to Fractal. If someone wants to see something change I'd recommend calling Fractal directly, and present the issues and logic and how the application and its interaction with the modelers could be improved, in an organized manner. Be someone who wants to make a positive change and you'll get a lot farther than beating your chest in public.