Yes the mainstream anthropological narrative is garbage, but this is too light on factual presentation to be considered a 'debunking'. It's basically just him musing about some possibilities. My understanding is that the genetic evidence establishes to a virtual certainty that even the other proto-human species had left Africa, only much earlier (unless an unlikely degree of parallel evolution was going on). Politically though, this to me is a moot issue since—in either case—we have been evolving separately for many thousands of years. The major race groups are in fact sub-species, and it is clearly our prerogative (perhaps even duty) to preserve our differences resulting from all that hard-fought evolution. Any answer to this particular question (as interesting as it may be) wouldn't change that.