The whole point of the DMCA takedown process is that it's rubber-stamp on the part of the service provider and all decisions regarding validity are left up to the courts. That's why there's a provision built into the law for the person receiving the claim to file a counter-notice to get their content reinstated. If Google is inserting themselves in the middle and denying claims because they don't believe that the person filing them is authorized to do so, I'm not sure whether that's proper procedure under the OCILLA.