I really don't know.
Truly, if you had been through this and were offered the chance in a court of law to get justice, as he did in 2005 - wouldn't you take that opportunity? Why wouldn't you take the opportunity to get justice?
Because of misplaced loyalty, perhaps? Also, Robson became a father himself two years ago and mentioned that having a son of his own was one of the things that made him reassess what happened and decide to come forward.