@LeeE
the problem is that the clause was unenforceable
No. That would be for lawyers (ultimately a court) to determine, and will inevitably vary between jurisdictions.
This actually means that anyone who distributes the updated microcode can only do so if they are in a position to enforce
"Enforce" in this instance meaning that you alert your users, by distributing Intel's notice. Putting it in an abandoned cellar behind a "beware of the leopard" sign (or perhaps something like in /etc/legalese/notices/intel/CVE-whatever-2018) should be fine, so long as they have it.