A fanboy comment is one that is backed up by no evidence, the 360 gpu is more powerful, the ati r580 series outpaced the g70 by some margin and the 360 chip is a slightly faster r580.
I fail to see any evidence from your side of the debate, where in the ops quote did it say that the 360 was more powerful? He simply stated it was more challenging, this is to be expected because it it harder to code for.
If you have a look around, lets say for example a quote from one of the lead developers of Mirrors Edge, saying that the CPU in the PS3 has allowed them to do things that other CPUs don't.
The 360 has the edge in terms of GPU, that's true, but in turn the PS3 has the edge in CPU power. It tends to even out.