Hawker, I suspect Knox wasn't ready in time, but the rest of the software and hardware was. I'm speculating of course, but I can t think of any other logical reason. It does seem odd that the bootloader was open on early firmwares up until comparatively recently.
Samsung Galaxy Note 3 SM-N9005
ROOTED STOCK FIRMWARE PHILZ TOUCH RECOVERY
"The only foolish question is the question not asked"-Anon