Quick checks are really not the way to do due diligence! Define a climate scientist! Koonin's scientific credentials are fantastic! Steve Koonin served as Undersecretary for Science in the US Department of Energy under the Obama administration. He has more than 200 peer-reviewed papers in the fields of physics and astrophysics, scientific computation, energy technology & policy and climate science. He was the professor of theoretical physics at Caltech, where he was also vice president. He is currently a professor at New York University. He clearly ticks the boxes of eminent scientist and academic - he does not dispute the underlying physics of anthropogenic global warming (most climate sceptics don't) - however, he does dispute the way that the science that feeds into the IPCC reports is subsequently misrepresented by mainstream media and politicians. He disputes that we are in a climate emergency - he sees a huge disparity between the actual data and the way that the data is misrepresented in subsequent summary documents and media headlines (I have read his book, and most of the material is drawn directly from IPCC published material - https://www.amazon.co.uk/Unsettled-Climate-Science-Doesnt-Matters/dp/B0948CBSY6/ref=sr_1_1?keywords=unsettled&qid=1690956367&sr=8-1
The negative review that you reference has been thoroughly debunked - yet it strangely still appears at the top of the Google searches on Koonin! You clearly haven't even had time to watch the video I posted. I have taken the time to read his recent book - he takes all of his evidence directly from the 'settled science' of IPCC data.
As for the negative criticism of his book, he challenges one of the listed authors (Andrew Dessler) directly at the end of a recorded debate with him - - this fellow academic initially denies having contributed to the piece that was published in Scientific American, until he is shown a slide with his name on it as a contributing author! Koonin is clearly, and understandably, very angry - he says:
"Inexplicably, the criticisms were based upon a review of the book, not what I’d actually written. They criticised 3 points I was alleged to have made. For example, they said I portrayed sea level rises as steady over time, when the entirety of ‘Unsettled;’ Chapter 8, if you've read it, is devoted to variations over the past century. Since Scientific American refused to publish a detailed rebuttal, I posted one on my 'Medium' page and it is worth checking out. But the great bulk of the 1000 words from those dozen ‘distinguished’ scientists were devoted to ad hominem attacks - for example, I was called a crank who is taken seriously only by far right disinformation peddlers, hungry for anything they can use to score some political points…really, Andy…you really think I am a crank, you really believe that? It is unfortunately typical of public discussions of climate and energy, when senior academics engage in name-calling they debase themselves and deny the public any real expertise that they have. It is the kind of thing people do when the facts aren't on their side…”
And that conveys a microcosm of the reality of what has been happening with the manipulation of the scientific debate - despite that negative review being challenged and clearly discredited by Koonin, it remains very easy for the public to find (as you did), who then take it at face value, believing it to be a credible source - unlikely to scratch beneath the surface!
Anyway, as Koonin explains in another interview, he is aware of the individual scientific criticisms and believes that he has effectively countered each of them - he has his own webpage called 'Medium', which I eventually managed to find, where he does publish rebuttals of criticisms, including the Scientific American one - https://steven-koonin.medium.com/ It is notable that when you Google 'Steven Koonin', the top result is that Scientific American negative review...but you have to hunt hard to find Steven Koonin actual page, in which he clearly discredits the Scientific American piece...funny that, almost as though Google is deliberately manipulating the information that you get to read!