[Nathan Zachary]

I would hazzard a guess and say they divert them there because it isn't a high population area.

[Hunble]

For those that do not know the transponder codes, and how easy it is to select the wrong one:

7777 Military, Interceptor

7700 Emergency

7600 Lost communications

7500 Hijack

1200 Visual flight rules

Now, if your radar controller told you to switch to something like 1523, it is rather easy to hit 7500 during the switching process. The pilot can only switch one digit at time on most transponders.