Actually, that's a prevalent misconception.
Recently the developer has suggested otherwise in about why they yet have a 64-bit version of DefenseWall and whether there will be one.
Short version: Ilya hasn't found an uncompromising solution -- he won't put his name to something that will not fully surmount the obstacles posed by Windows' 64bit Kernel PatchGuard.
NOTE WELL: in post #42 in the thread suggests he's working on it.