I do agree that the shape can impact rigidity but not in the same way. I've asked to see the study and will be chasing this with Imperial College London.
However, the validity of this idea of "rigidity in twisting" is greatly dependent upon the method the Imperial College London used to test the twisting. If it's what I think, then I fear they've provided GN with useless data.
It's important when explanations like this are offered, especially with reference to scientific research, that the evidence is provided for scrutiny. Otherwise we get a "BIG BAT = POWERFUL BAT" myth being propagated.
I mean no offence to GN or Chris, I have nothing but respect for them.
EDIT: I would like to say, I enjoy it when bat makers come up with theories. It shows they're thinking and opens up debate on a craft I love.