(1/2) I could name a couple of arguments against it
1. Neanderthals' most recent common ancestor is much farther away than humans' most recent common ancestor. And even the status of neanderthals as a different species has been debated up to the present day due to not fitting the biological definition for different species. You'd have a much harder time arguing that is the case for populations of humans who are much more closely related and undoubtedly make fertile offspring.
2. IQ alone is insufficient to qualify for species differentiation. Any single parameter is. There are Europeans born as far as 2 standard deviations apart from each other, but you won't argue they're different species.
3. The figure 62 comes, to my knowledge, specifically from Richard Lynn, who takes a lot of methodological freedoms when coming up with IQ values. If
https://www.human-intelligence.org/australian-aborigines/ are his sources, I invite you to look at each individual one. The first 4 precede the WAIS and many are in fact not IQ tests (Lynn has been called out before for extrapolating results from sources like test scores in Apartheid-era South Africa). Some are even coming to the conclusion that abos and low SES white children perform similarly (
https://journals.sagepub.com/doi/10.1177/002202217100200409 ) A few more are done on aboriginals as remote as possible from civilization, and some are even studying people with nutritional deficiencies (
https://psycnet.apa.org/record/1985-27090-001 ), which are reasonably more likely to exist among people who don't live in urban areas at the grasp of the welfare state. It doesn't take a genius to imagine how such things may impact cognitive test results. This might be like comparing pre-industrialization Germans to modern Germans and concluding their height difference makes them different species.
