Rule 26. Duty to Disclose; General Provisions Governing Discovery
(B)
Specific Limitations on Electronically Stored Information. A party need not provide discovery of electronically stored information from sources that the party identifies as not reasonably accessible because of undue burden or cost. On motion to compel discovery or for a protective order, the party from whom discovery is sought must show that the information is not reasonably accessible because of undue burden or cost. If that showing is made,
the court may nonetheless order discovery from such sources if the requesting party shows good cause, considering the limitations of
Rule 26(b)(2)(C). The court may specify conditions for the discovery.
The RNC would need to show "good cause" of what's on the server to be germane to the claims against them.
The Russians have "good cause" since they're accused of having broken into it.
Ironically, for the RNC to collude with the russians in mounting such a defense would only help prove the previous conspiracy.