I agree there is an apparent conflict in the guidance at FAR 46.316 for R&D contracts that do not involve supply items. It is possible the clause is meant to account for possibility that supplies may be added to the R&D contract during performance, but that's pure speculation. I can't find any applicable waivers or exceptions. In any case, it is simple enough to include it…just to cover your bases. Sorry I couldn't provide more insight.