Normally, these discussions are kept secret. Not because discussing them in public might violate the rules but because making proffers public seldom makes tacticalsense. In discussing Lewinsky's proffer, Ginsburg suggests that Lewinsky either has already lied or will do so in the future for the right deal. This doesn't look good.
But these contradictions cannot be used against Lewinsky at trial. The federal rules of criminal procedure prohibit the government from using any statements made in furtherance of a plea bargain, and Lewinsky's attempt to gain immunity is essentially a form of plea bargaining. Additionally, most proffer sessions involve what is known as a "queen for a day" agreement, under which both sides agree that information discussed at such a session will not be admissible against the defendant at a trial. These protections, enacted to encourage truth before trial, have the paradoxical effect, when publicized, of making Lewinsky appear crazy, mendacious, guilty, or some combination thereof.