WMAP polarization data vs. Quasar spectra?

i understand, that the detection of (partial) polarization, in CMB photons, by the WMAP, implies a high column density, of (ions &) electrons, along the LOS to earth. So, the conclusion has been reached, that Reionization "must" have occurred early (z~(30-10)) so as to force CMB photons to propagate through hundreds of millions of years more ionized plasma, as compared to Quasar spectra, which date Reionization to later epochs (z~6).

Column density is the (integrated) product of number density times path length. Would a higher baryon density ([math]\Omega_B \rightarrow 1[/math]) admit a lower Reionization redshift, i.e. shorter path length, so reconciling WMAP to Quasar spectra?