I absolutely don't know, they released it literally "as it is", without any improvements ... Ask that to them.So why it's still like that? if TWLnf can work, the downgrade and/or sudokuhax/4swordshax injection could be faster and safer.
BTW, I've found the updated payload, now twlnf should work :
https://gbatemp.net/threads/hiyacfw-discussion.478848/page-44#post-7509380
Thanks to @Billy Acuña