It's hard to tell if "complete idiot" refers to the intelligence level required for the book or the intelligence level required for the job.
Ugh okay so the joke is a slightly lazy and seems a little spiteful. Statistic after statistic shows that attractive people don't get preferential treatment in the workplace. The humor is probably intended for people who are desperate for cheap scapegoats as to why they don't get called back after interviews. BUT we can all agree that men act like obsequious emotional cripples in front of big-bewbed women, amirite?