Personally, I think this whole topic is BS. As those of us in this niche of the hobby tend to be more on the subjectivist side, if anything like this study existed, we would have most probably been hit over the head with it so many times that we'd all be parroting it.
As a former material scientist/chemist, I think he is probably mistaking rubidium for either rhodium or ruthenium, both of which are among the 8 precious metals. It makes little sense to plate a precious metal (silver) with a non-precious one (rubidium), but commonplace to plate non-precious metals (copper, nickel, etc.) with precious metals (silver, gold, rhodium...).
As a former material scientist/chemist, I think he is probably mistaking rubidium for either rhodium or ruthenium, both of which are among the 8 precious metals. It makes little sense to plate a precious metal (silver) with a non-precious one (rubidium), but commonplace to plate non-precious metals (copper, nickel, etc.) with precious metals (silver, gold, rhodium...).