For the record, $300,000 is nothing if this is true.
Additionally, while my trade is PE, there is enough legal mumbojumbo incorporated in it when it comes to legal terms for me to realize the potential of dangling a number that is high for the accuser but low for the accused. For instance, in PE one can fire the Manager 'for cause' (they made a material breach) or 'without cause' (you don't like the Manager, returns, management, etc and there is a mechanism to divorce the Manager from the Fund). Now, doing it with cause is difficult as the standard of proof is high, and you could even potentially spend a lot of time in court proving cause, but without cause is the simpler (and more used) option.
Now, what does all that have to do with the price of tea in China?
Well, imagine I go accuse some big-shot, claiming he/she/it did some unnameable stuff to me a decade and a half ago. I then ask for US$300,000. Would it be better for the person to settle out of court, and pay me some commensurate amount, or to risk going to court and - guilty or not - having all sorts of nasties laid out in public? It is the same reason even large corporations settle out of court, even when it comes to cases they may easily win, rather than trying to trade blows publicly, and potentially attract other people/entities/attention to the fray.
Now, there is a FReeper who said that the Singer chap has had a number of other accusations, and that he is not a nice chap. Thus, he may be (and is most probably) guilty of what he is being accused of, and as I stated earlier I have no dog in the fight. If he's going around messing up little boys he needs to be thrown in a dark hole. No question about that.
The only reason I posted initially was to ask what the standard of proof is for someone to make a claim against someone else.