An anticheat assumes some specific layout of KiUserExceptionDispatcher (in an 64 bit app). After checking two bytes (obviously instruction opcode) at (KiUserExceptionDispatcher + 1), it extracts memory address from this instruction and places its hook function address at that address, expecting that to be called on CPU exceptions (but not software raised exceptions).
I tried to make something out of it so supporting this mechanics is not completely artificial and fits into our implementation. I don't know if that hook has really something to do with wow64 in Windows implementation (while I guess that's possible), but it seems to me in our implementation doing it this way is a bit more straightforward. Specifically, it seems to me a bit easier to follow when a single function (KiUserExceptionDispatcher) doesn't mix different unwind models (while having the same runtime function info).