I've modified the kali-arm-build-scripts to produce encrypted images for rpi2.sh. While setting up the image on an x86_64 arch machine, the NUKE key applies properly:

cryptsetup -v -q --cipher aes-cbc-essiv:sha256 luksFormat ${rootp} .tempkey
cryptsetup -v -q --key-file .tempkey luksAddNuke ${rootp} .nukekey
cryptsetup -v -q luksOpen ${rootp} crypt_sdcard --key-file .tempkey
rm .tempkey
rm .nukekey

This code works as expected and properly produces an encrypted image that works perfectly.

However, when applying the "Nuke Key" on the rpi2, the nuke key unlocks the volume and does not produce the expected behavior of wiping the keys.