I do agree with victim interests in sex cases, and a reluctance to testify. And I do agree as to the victim motivation for the agreement, although I expect there may be more reasons than an admission of guilty to explain the necessity of the agreement. Similarly, the existence of such an agreement, if proven, would suggest details embarrassing to Incognito.
With that said, and with reference to your discussion directed to the post to which you responded, I am not sure what your experience is (50 states and the feds do things differently, so you may have a different experience) once a criminal complaint is filed with the police, as appears to be the case here. I have not seen a confidentiality agreement kill a criminal prosecution (to include prosecutions of sex offenses - my experience is federal) once that complaint is filed with authorities. What that Florida attorney states in the link I provided is consistent with the federal criminal approach - the victim's reluctance to testify will be weighed by the prosecutor in determining whether to prosecute or not prosecute (I know some States permit a victim of crime greater authority in determinations as to whether to press forward as that decision to press charges is an essential component of the charge). In this case, the victim appears to be the complainant, not a guardian or third party to the victim. If the prosecutor decides to go forward under a system approximating the federal system, subpoena authority will make up the victim's mind if that person is essential to the case (they will testify on pain of contempt if incapable of asserting a testimonial privilege). I have seen that first hand in practice. Interests of justice at the system level preempt individual concerns.
In the federal system, victims' rights permit victim statements at material portions of criminal prosecutions (bond hearings and sentencing). They provide for restitution awards. They do not take the case from the prosecutor, and thereby derail prosecutions. I suspect, in a State system in which a victim's concurrence in a prosecution is essential to the State's decision, that contracts to purchase the victim's silence are inevitable (I still think Big Ben may have availed himself of such an arrangement to kill that case, given the PO'd prosecutor and his public address at the end of the case). If Florida has such a system, that may be the case here. If not, then the Florida subpoena would force the testimony as a matter of criminal procedure if there ultimately was a case to prosecute.