You don’t think all the scientists and engineers working around the world on this problem aren’t aware of the potentially fatal issues?

Scientists catalog what we know and don't know and try to chip away at the list of things we don't know. The whole point of the book and this article is that there is way more stuff we don't know than we realize and most discussion of space colonization tends to forget the parts we don't know.

The article even pointed out some very showstopping issues:

No one has been conceived in low gravity, no fetuses have developed in low gravity, so we simply don’t know if there is a problem. Astronauts experience bone and muscle loss and no one knows how that plays out long term

I was shocked to learn that no one really knows how to construct a long-term habitable settlement for either the Moon or Mars. Yes, there are lots of hand-wavy ideas about lava tubes and regolith shielding. But the details are just… not there.

For instance, supposedly space will end scarcity… and yet, any habitat in space will naturally have only a single source of food, water, and, even more urgent, oxygen, creating (perhaps artificial) scarcity.

Space colonization may happen, but it's incredibly doubtful that it'll happen in our lifetimes.