Men exist. Women exist. The characteristics that define them as different from each other would (and will) exist whether we acknowledge them or not, so they are not social constructions. This is a fact.
Masculinity is the set of the most common characteristics of men which differ from the most common characteristics of women. Masculinity is observed, not constructed, and women cannot participate in nor even truly understand it. Women can only participate in and understand femininity. Of course, pretending to be a man has no impact on either one because such behavior is extremely uncommon.
In other words, this book is a compete waste.