If it's so obvious that he molested those kids, why couldn't they prove it in 2005? Not all nut cases are pedophiles and not all pedophiles are nut cases. Most of them appear quite normal actually, that's how they manage to get close to kids in the first place.
It's not at all unreasonable to think someone might allow their child to stay at his ranch (knowing full well what his behaviour is like, face it, everyone knows how eccentric he was) child has a fun time, make an accusation and cash in? As it's been pointed out several times, what parent who honestly believes their child was molested takes a payout? Get the creep behind bars then seek monetary reward.