Seems to me that a simple assessment of order of operations is necessary to resolve this.
If the Prosecution wants to prohibit Eisenman from bringing up the kidnapping and sex trafficking, they first need to prove that it either never happened, or Mr. Sorenson was not involved (and someone else was involved).
If the Prosecution first prosecutes that case, then those findings would be admissible in Eisenman's prosecution and defense. Of course this means that Eisenman then sits behind bars with no trial happening for himself and arguably his right for a speedy trial is compromised.
I could even see certain defense lawyers agreeing to it though; if you have a blatantly guilty defendant and your main objective with a trial is to obtain a lesser offense conviction and lower period of imprisonment, you already know you're going away for years. If it takes a year or two to get to trial you forward that wait-time in prison as time served against the lesser sentence if you win. And the outcome of that trial would be quite mitigating to your own pending trial.
And I'm sure Mr. Eisenman would love to have a court conviction against Sorenson, even if posthumously awarded. If for no other reason, his daughter can then use it to pursue damages against Sorenson's estate if such a thing might exist. Not to mention a salve to his own conscience that other parties agreed with his motives, if not with his actions.