The industrial design doesn't have any bearing on what components are inside.
If this ran software at all (Apple tends to develop the two in isolation: no doubt around this time some people were working on touch interfaces, but nowadays the two don't tend to meet until they're quite far down the line) then I suspect it would have been test software similar to Switch Board, which they install on prototypes at the moment) unless it's pretty close to production.
I would be surprised if this was running G4. Apple's dissatisfaction with IBM was growing circa 2003-04 and if they were noodling around with the form factor they would have been under no pressure to put in a production CPU; they'd have gone with the best technical solution to the problem (which I doubt is a G4. Might have been another IBM chip).
