Still stands - 25% skin weight is no where near 25% fuselage weight.
Did you look at the formula?
So the paper is really saying that the weight of a skin without windows is 25% less than that of a skin with windows. It doesn't take into account frames, bulkheads, or anything else that makes up a fuselage.
Did you look at the formula?
What exactly do you think
Window metal frame and
near hole reinforcement are? Structural elements perhaps?
Perhaps if you READ the article, you will comprehend where the 25% comes from, or you could continue to blindly argue your point when provided with facts to the contrary.