>How does that apply when you're releasing the source code in the jurisdiction where the law requires it?
That would depend on what exactly the requirement is and what exactly the third-party code is and is used for. Without the specifics, I'd say it seems plausible that the third party itself is not subject to the requirement but the firmware using the third-party code may be subject for both first- and third-party code.
But then why is that a problem? The entity in the jurisdiction releases the code for the device they sell in the jurisdiction, whether they wrote it or licensed it, and doesn't license it under terms inconsistent with their legal obligation.
That would depend on what exactly the requirement is and what exactly the third-party code is and is used for. Without the specifics, I'd say it seems plausible that the third party itself is not subject to the requirement but the firmware using the third-party code may be subject for both first- and third-party code.