I dunno, we can't ask him.
Again, people run for all kinds of reasons. Most because they're scared and stupid.
Or because they think they'll get a beat down like this if they stop and spread eagle & then hands behind the back: http://www.nbclosangeles.com/news/local/Man-on-Stolen-Horse-Stunned-by-Sheriffs-Deputies-in-IE-299250951.html
FR thread on the topic: http://www.freerepublic.com/focus/f-news/3277654/posts