Well if a statement like that is the Jury instructions I guarentee the verdict will be overturned. The jury is the trier of fact not the judge.
I believe what he meant is that he is not tossing out the kidnapping charge because there is in fact proof that she was in the motor home and that if the jury decides that her fingerprint was placed in there the day in question then they may find him guilty of kidnapping unless they have other overwhelming evidence to induce reasonable doubt in their mind.
Here is a link to Ito's Jury instructions for the OJ trial (it was the first example I came across in a search and would not have been my first choice to use as an example):
http://www.lectlaw.com/files/cas62.htm
Of particular interest to me was the reasonable doubt detail, comments on circumstantial evidence and how to evaluate expert witnesses.
"Both direct evidence and circumstantial evidence are acceptable as a means of proof. Neither is entitled to any greater weight than the other. However, a finding of guilt as to any crime, may not be based on circumstantial evidence unless the proof circumstances are not only one, consistent with the theory that the defendant is guilty of the crime, but two, cannot be reconciled with any other rational conclusion. Further, each fact which is essential to complete a set of circumstances necessary to establish the defendant's guilt, must be proved beyond a reasonable doubt. In other words, before an inference essential to establish guilt may be found to have been proved beyond a reasonable doubt, each fact or circumstance upon which such inference necessarily rests, must be proved beyond a reasonable doubt. Also, if the circumstantial evidence as to any particular count is susceptible of two reasonable interpretations, one of which points to the defendant's guilt, and the other to his innocence, you must adopt that interpretation which points to the defendant's innocence and reject that interpretation which points to his guilt. If, on the other hand, one interpretation of such evidence appears to you to be reasonable, and the other interpretation to be unreasonable, you must accept the reasonable interpretation and reject the unreasonable."
"In examining an expert witness, counsel may propound to him or her a type of question known in the law as a hypothetical question. By such a question, the witness is asked to assume to be true a set of facts and to give an opinion based upon that assumption. In permitting such a question, the Court does not rule and does not necessarily find that all the assumed facts have been proved. The Court only determines that those assumed facts are within the probable or possible range of the evidence. It is for you, the jury, to find from all the evidence whether or not the facts assumed in a hypothetical question have been proved. If you should find that any assumption in such question has not been proved, you are to determine the effect of that failure on the proof Excuse me. You are to determine the effect of that failure of proof on the value and weight of the expert opinion based on the assumed facts. In resolving any conflict that may exist in the testimony of expert witnesses, you should weigh the opinion of one expert against that of another. In doing this, you should consider the relative qualifications and credibility of the expert witnesses as well as the reasons for each opinion and the facts and other matters upon which it was based. In determining the weight to be given the opinion expressed by any witness who did not testify as an expert witness, you should consider his or her credibility, the extent of his or her opportunity to perceive the matters upon which his or her opinion is based and the reasons, if any, given for it. You are not required to accept such opinion but should give to it the weight, if any, to which you find it to be entitled."