IMO, if the Defence even want to raise it, they would make an application to the court to do so before trying to introduce it. The court will not re-open an almost 20 year old kidnapping charge that was dropped. It would effectively require all the Ws in the kidnapping case to be called in Casey's case, and the Judge will not let that happen. The defence look like they are grasping at straws by attacking him....first Jesse, Amy, Ricardo, TonE, now RK. Seems like they will try to make anyone a suspect.
At the end of the day, there is so much evidence against her that there is no way this will matter. Just the fact alone that she claims Caylee called her the day before her arrest, and the fact that the police can prove that she didn't receive the call, combined with lying about the "nanny's addresses", partying at fusion, saying Hawkins child was also babysat by her etc etc. I think people are losing sight of the real issues in this case if they are focusing on RK.