You are correct, the program's main executable is 32 bit application.
However, PowerTools is fully compatible with 64 bit systems and can access the 64 bit area of the system. The fact that the program itself is 32 bit application only means that PowerTools can only use a certain amount of system memory (RAM), since the program doesn't really need that much memory, we haven't seen a need to release a 64 bit version of the executable.