Right now, it is too soon to say whether Goldman actually committed fraud. The charges are allegations. They need to be proved.
IMO, the key issues turn on the design of the CDO in question and disclosure related to that CDO. If all of the instruments included in the CDO were a subset of a larger group selected by Mr. Paulson, then that is a material element that would need to be disclosed to prospective investors. If there was a material omission, was it deliberate? Only when those facts are available will the allegation be demonstrated or rebutted.