The nerd snipers problem

We correct errors that appear throughout "The vicious neighbour problem" by Tao and Wu. We seek to solve the following problem. Suppose $N$ nerds are distributed uniformly at random in a square region. At 3:14pm, every nerd simultaneously snipes their nearest neighbor. What is the expected proportion $P_N$ of nerds who are left unscathed in the limit as $N\to\infty$?
Comment: 10 pages, 1 figure, 3 tables. Comment on DOI 10.1088/0305-4470/20/5/008 (R Tao and F Y Wu 1987 J. Phys. A: Math. Gen. 20 L299)