The question that is whether the assertion that diluting the value of gold by introducing to serve as a second currency actually did improve the lot of the less wealthy. Historical evidence suggests that a fiat devaluation hurts the poor (well ultimately it hurts the rich when the poor overturn the wealthy in revolution). Moreover, the architects of this policy failed to see in-retrospect-obvious problems like arbitrage destabilization of bimetallism as the gold-silver exchange rate was, effectively fixed by law. Suffice it to say my confidence in their ability to be correct about the complex net social effects is low, given they missed this crucial, first-order economics problem.
Backers of bimetallism knew it would "dilute" the value of existing currency (i.e., would cause inflation, with subsequent known negative effects). They did not "miss" that, or overlook it; they accepted it as part of a tradeoff. They knew there would be some pain at the outset, but believed that the eventual outcome -- of increasing the number of people who could turn metal into legal tender at a favorable rate, and breaking up some of the power of established wealthy interests -- would outweigh that pain through resulting economic mobility and wider-spread prosperity.
Hence the argument for "trickle up", effectively, as opposed to "trickle down".
