What he says is that " ‘Mbuti’ ancestry represents the total of ‘Deep’ ancestry from lineages that split prior to the366 split of Ust’Ishim, Tianyuan, and West Eurasians and can include both ‘Basal Eurasian’ and367 other (e.g., Sub-Saharan African) ancestry. "
So, there could be "extra" Basal in there, a lineage that split before Basal, as well as any modern SSA or East African in people. Remember the SSA that used to show up in ancient samples? If the algorithm spotted something really old it threw it in SSA perhaps.
He has no sample for these deep lineages that include not only Basal Eurasian but other lineages that split off before Basal. There's also the language about bottlenecked and non-bottlenecked lineages. Which one was which, the Basal or the pre-Basal? What was the bottleneck, what caused it, where?
Looking at this graph I'm struck by the Dzudzuana in the more "eastern" hunter-gatherers, like Ukraine, Norway, Sweden, Russian Mesolithic, Motala and Iron Gates. Movement westward from the Caucasus? Or straight from Anatolia?
Part of that is Basal Eurasian.
You can also see it in the graph of the amount of Basal Eurasian. According to that, the hunter gatherers had what looks like from 1 to 10%, which is just about what the Feldman et al (Krause) paper on Anatolian hunter-gatherer transition to farmer said would be in the ball park for the amount of Basal Eurasian that would need to be in Iron Gates if there had been movement from Anatolia to Europe at that period. Of course, they only found something like 1.6.
I believe even Mata needs CHG admixture.