The guidelines are likely VERY broad. NiFong used the probability of him fleeing to justify the bail. Where the heck is the kid going to flee, too?? He's gonna live some secret life on some deserted Island? The kids wants AND NEEDS the protection of his parents. The idea that he would flee is absurd.
Seems to me the judge must've believe Nifong had an argument that the kids would flee or he wouldn't have set the bail so high. On the other hand, all three made bail so they can still skip.