Dumbest canard ever. The whole freaking point of the 3/5 rule was to limit the power of the slave states by reducing how much they could pad their population count with slaves. It made no distinction as the the relative worth of the individual, it was intended to prevent the slave states from running roughshod over the free states in the House of Representatives.
You sure it wasn't the other way around? The free states didn't want to count slaves as part of the population so that they could run roughshod over the slave states?