My reading of the situation, and I could be wrong is that the Knox flag and therfore the e-fuse are tripped by rooting, during rooting. Not by unlocking the bootloader, but the actual rooting of it. No matter what you do if the device is rooted (and I doubt there are many different ways to root) the actual process of rooting trips it. Next to impossible (but I live in hope) to circumvent.
Samsung Galaxy S4 GT-I9505
ROM STOCK UK -I9505XXUEMJ7 UPDATED FROM STOCK 4.3 VODAFONE WITH ODIN KNOX STILL 0x0
Samsung Galaxy Note 3 SM-N9005
FOR NOW: STOCK FIRMWARE