> See, that right there is where the analogy falls apart.
You're missing the point. That's the _goal_. If they hadn't mentioned that was the goal, would it still be illegal?
> Writing software to translate between two independently-developed programs is not, last I checked.
It is illegal if the license doesn't permit you to do that. Copyright owners can place restrictions on usage of their works.
See, that right there is where the analogy falls apart. Tax evasion is (usually) illegal. Writing software to translate between two independently-developed programs is not, last I checked.
"If the end result is a de-facto derivative"
You'd need to prove the blob is derived from Linux. If it's not, then there's literally nothing illegal happening here. If it is, then - again - the shim is not the illegal thing; the blob is, and the shim is entirely irrelevant in that illegality.
The usual reason for the shims, by the way, has very little to do with licensing terms (at least not directly) and very much to do with the fact that Linux does not provide a stable API (let alone ABI) for kernel modules. The intent of the shim is therefore almost always technical rather than legal in nature.