Although you can argue that we already do it because we, as a species, reproduce.
It could be quite possible that our level of intelligence is not reproducible by the means we have chosen. It could be that there is something inherent in our entire composition that allows for our particular expression of intelligence and consciousness.
I'm not saying it's impossible. I am saying that first, we don't even know what we're looking for. And when pressed as to what that is, the answer comes down to basically, "You know..." while gesturing broadly.
I'm very much sympathetic to the idea that there could potentially be aspects about the specific structure of a brain that is necessary to produce intelligence, or at least necessary for sentience. But does not inherently make it impossible to reproduce. For it to be impossible to reproduce a brain, there would need to be something in the cellular machinery used to construct a brain that we can not pick a party and replicate.
As a reminder, the argument made in the article is that it is impossible even in principle, not that it is impossible to do it using a digital computer of typical current architecture.
Tell me what it is first. Define "artificial general intelligence" in a way that is generally accepted.
Is it possible? I don't know because I don't even know what we're trying to do.
That there is a tough engineering job involved in reproducing such machinery so we can grown brain matter at will, and that we'd prefer our computers to be less squishy does not mean it is likely to be impossible to reproduce it.