Employees of the Crabtree Mall Barnes & Noble used a Tuesday book-signing by science-fiction author Orson Scott Card as an opportunity to mock those in attendance. ''Excuse me, Mr. Card,'' cashier Randy Feig said to coworker Ian Rose in a derisive, pinched 'nerd' voice. ''In Shadow Of The Hegemon, why was Ender Wiggin so reluctant to return to Earth after the Formic War?'' Feig then urged Rose to 'check out the huge dude in the cloak' in the second row. 