How do you 'steal' a machine that is a System-on-a-Chip? The case, LCD selection, control method, etc. are the only real design issues to make; and they're not things to be proud of, either. I'd want to wash my hands of responsibility for most of what was packed AROUND the MMSP2.
In the case of the GP2X, GPH apparently just cloned Magiceyes' example design for an MMSP2-based "PMP" machine and put it in a more compact and portable form factor. That's not really creative design or something to steal, and it's Magiceyes' design, not this person, whomever he is ...
If he's referring to the GP32, there is more engineering involved but still not all that much given that it's just a Samsung combo-chip, but the ARM processor appears to be discrete. Pardon me if I have something mixed up there, I'm not as well versed regarding the design of the GP32, as I wasn't around here during its hayday ...