Discovered this unfortunate thread (https://forum.osdev.org/viewtopic.php?f=8&t=13810) (archive (https://archive.ph/oOMYH)) from their FAQ about content licencing. It was posted forever ago (2007), but absent any further discussion or bona fide licencing efforts on the wiki meta itself, we must sadly assume that this is their administration's current policy.
TL;DR: OSDev wiki content is copyrighted by its authors, the editors, and may not be copy-pasted into our WiredWiki.
All websites are mortal, including OSDev, and including ours. Work must be done to port over all of the information on their wiki to ours where it will be licenced better, because while the text is protected by copyright, the underlying knowledge is not.