Maxwell’s Objection to Lorenz’ Retarded Potentials

Maxwell seems to have considered the great paper of L. Lorenz on retarded potentials [1] (published simultaneously in 1867 with a paper written in 1858 by B. Riemann on the same theme [2]) as insufficiently supportive of his vision of a dynamical theory of the electromagnetic field [3], whereas the present attitude is that Riemann and Lorenz made important contributions to the Maxwellian view. Maxwell made an objection [5] (p. 651) that if a pair of equal and opposite charges move collinearly, then the retarded potential experienced by the charge in front has smaller magnitude than that experienced by the charge in the rear because the former retarded distance is larger than the latter; hence, there must be a net electrical force on the system, which accelerates it without limit, providing an infinite source of free energy. Is Maxwell’s objection valid?