I think that Kalai here is very seriously understating how fringe/contrarian his views are. He's not merely stating that there's too much optimism about potential future results, or that there's some kind of intractable theoretical or practical bottleneck that we'll soon reach and won't be able to overcome. He's saying that any kind of quantum advantage—a thing that numerous experiments, from different labs in academia and industry, using a wide variety of approaches, have demonstrated over the past decade—is impossible, and therefore all of those experimental results were wrong and need to be retracted. His position was scientifically respectable back when the possibility he was denying hadn't actually happened yet, but I don't think it is anymore.

I think he is playing it smart. The more fringe/contrarian it is, the bigger the payoff if he turns out to be right. So far nothing of much use came out of QC, and if nothing will, then the hype pendulum swings back at some point, and he will win big. If not, his position will seem silly, but not much risk to his reputation, being skeptic of a new model is intellectually fine and even courageous if it goes against the mainstream. I see it as those who called out "replication crisis" in social sciences.