Oregon Tries an End Run Around Crawford?

CrimProf Blog writes up a story about a criminal procedure professor in Oregon who drafted a law recently passed in Oregon which amends its Rules of Evidence to allow hearsay statements made my an alleged victim to be admitted, over a Crawford confrontation clause objection, if the victim's unavailability was caused by the defendant (by threats of retaliation, for example). It would have been nice if the little article actually provided the text of the rule, because from just reading the article, it sounds terrible. First of all, the Crawford decision was explicit in stating that the Rules of Evidence do not and cannot trump a defendant's 6th Amendment Confrontation Clause right to cross-examination. Second, how exactly does the State prove that the declarant's unavailability was caused by the defendant? Obviously, there may be instances where there is another witness to threats made by the defendant--sometimes it is the arresting officers. But is another witness required? Or is it enough that the declarant has told others--such as friends, family members, or prosecutors--that she is not appearing because of a threat of retaliation by the defendant? If it is the latter, isn't that bootstrapping of the first order?