Thanks for asking!
I suppose we could have been more explicit in the original announcement post, but the relevant line is this one:
That includes the gates of Ahn’Qiraj; they’ll be open. The war effort will be marked completed. The gong will already be rung. The Anubisath warriors will already be beaten back. The fresh Wrath of the Lich King realms will not mint any new Scarab Lords.
If you want to be a Scarab Lord, consider organizing the effort on a low-population Season of Mastery realm. Last I checked there were a few with their resources completed but their gongs unrung… 