As you already realized, cracking this is no problem at all. I think "security through obfuscation" applies here. Never do this, when there is a better way of solving your problem!
The reason for cpu to work with your hash is the one I already mentioned. The GPU versions have optimized kernels for every PSA. A CPU is much easier to handle and doesn't need these optimizations (or doesn't profit that much, because it's slower).
The reason for cpu to work with your hash is the one I already mentioned. The GPU versions have optimized kernels for every PSA. A CPU is much easier to handle and doesn't need these optimizations (or doesn't profit that much, because it's slower).