To be sure, the absence of fossils doesn't mean anything in itself. We're only been hunting them actively for maybe two hundred years or so -- perhaps a little longer but not much longer -- so it could just be that nobody's thought to look. Or, as you point out, the conditions weren't right to allow for many (if any) fossils to be formed in the first place.
I don't have any particular reason to doubt this discovery, or to be attached to the "Out of Africa" theory, other than that being the one I learned. So, yeah -- interesting, not yet convincing, but certainly well worth reading and thanks for bringing it to my attention!