i believe that the earlier source for this would be cavalli-sforza. i don't see anything in here that wasn't developed by him more than 20 years ago.
and, cavalli-sforza was of course drawing on gimbutas for her archaeological work in central asia.
if you want a gentler introduction, there's a text by jp mallory called "in search of the indo-europeans" that i found very useful when i was studying this ~20 years ago. it's from 1989.
the major problem with these models - and this guy is not the first person to do this - is the assumption that the rate of mutation is constant. there's really no reason to think that, and it's no doubt horribly wrong. that said, we don't currently have a better idea, either. we could, in theory, try to model the rate of change by looking at snapshots of actual dna, but we're in a kind of circular logic problem with that, as we have to assume constant rates to do much of any analysis. but, it's still the better approach, and it will need to be done, eventually. until then, these models can come up with approximations, and they can help give us clues, but they shouldn't be taken particularly seriously. and, they definitely shouldn't be used to try to test hypotheses, where errors in modeling rates could very well affect the deduction presented by the model. so, i don't want to write this off entirely - largely because he's just redoing things that were done decades ago, or much longer than that, and just confirming the results we already knew. but, the premise that this is some kind of giant advance is an exaggeration - it's a baby step, and it doesn't address the longstanding, pre-existing problems with assumptions in the modeling.
if you want to look into this, look up the (unresolved) gould-dawkins debate to start.
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when i was working this out at the time, i became convinced that the historical elamite civilization was probably south asian in origin. linguists have proposed a theoretical elamo-dravidian language, but they generally derive it the other way. so, it's useful to envision an ancient south asian civilization that was centered in the harappan space but spanned the distance between mesopotamia and china, and trade links all along the path. local derivations of south asians in iran need not be recent immigrants.