The backdate(backwards compatibility) software to play PS2 games is available for free right on the sony online store as a download. It’s not in the other models, nor can it be simply uploaded to say a 40g or one of the newer units. however if he managed to unlock the core of the system to allow it to be loaded into it then it’s possible…it’s just code.
It’s like playing PS1 games on the ps2
just saying…