Now mix GPLv3 code with the Linux kernel without violating an FSF license. Of course that you cannot release the result just means that there are also zero users, so the freedoms of those zero users are preserved.

Edit: I am not arguing from an ideological standpoint, just from the resulting compatibility and usability issues. The GPL 2 and 3 were both written to protect the four freedoms, that they are incompatible and that we now have to invest time and effort work around that even for free software is just ugly.

That would be my question? It introduces an incompatible split with existing code that cannot be re-licensed by hand wave of the FSF for purely dogmatic reasons.