> When you put a PPC CPU on a motherboard, it turns into an Amiga.

I don't think so. Before the Pegasos II was supported by OS4, it surely wasn't considered an Amiga by OS4 fans. This changed virtually overnight. Accordingly, the Pegasos I never seemed to be considered an Amiga. So the criterion for them seems to be the (announced) support by OS4, which makes sense if you think about it.