The change is still under NDA. If you sign into your Apple dev account and look up the WWDC talk on OS X kernel extension development, you'll find it within that slide deck.
Deep, I know.
I also reported the issue to the VirtualBox team many weeks ago and they confirmed the bug and know it exists. It just seems like it wasn't important enough for them to fix prior to release.
Honestly, the fact that the change is under NDA seems like reason enough for them to not bother yet. Who knows what NDA violation an open source project could make in discussing how they are going to implement it.
I know what NDA violation they could make. It is called "NDA violation". It is where you sign an NDA and then you disclose information. Release of source code could be considered a disclosure. Now Apple can go right ahead and do a whole lot of nothing against VirtualBox and Oracle because no one cares. Neither should you. Stop lionizing contract law. It is a civil matter and no big deal almost always and especially when no money has changed hands.
Deep, I know.
I also reported the issue to the VirtualBox team many weeks ago and they confirmed the bug and know it exists. It just seems like it wasn't important enough for them to fix prior to release.