I had a look at the power levers and go-around buttons in question today and I believe I have the answer.
Smiert Spionom is closest to the correct answer.
It appears to me that if the No.2 power lever were the same size as the No.1 then one would indeed get ones finger caught between the No.2 power lever and the No.1 condition lever.
But it is this part of the No.2 power lever which is reduced in length.
I think there is something in the rules about go-around buttons being positioned on both power levers which ATR were probably not aware of and tried to get away with just having the one on the No.1 power lever.
Mystery solved!