I just read the whole book. Here are my comments:

1. "Pilgrims." The author consistently makes comparative references to pilgrims to the American continent. This is disingenious.
For the homesteaders, the cost of expansion was very low. Their technological advantage allowed them to drive out the native inhabitants with relative ease. Their infrastructure requirements were minimal, but most importantly, there was fruitful land to be taken at very low cost.

Not so with seafaring. Your "land" must be planned and built up-front at substantial cost. Once you've built your "land", you're stuck with that design. You can't just take more "land", since it would require building an entire new platform, once again at substantial cost. What happens when your platform capable of supporting 1000 people can no longer support its growing population? Do you kick people off? Who decides who stays and who leaves? And who would be willing to live with the sword of Damocles over their heads, knowing that at some point in the future, they could be ousted by the council of elders, forced to leave their home and friends, to fend for themselves?

2. Maintenance. The author is very opposed to taxation, and yet the very nature of seafaring incurs substantial maintenance costs. Who will bear those costs? Who will collect the funds? How will you handle disputes over the taxation rate, or people who refuse to pay?

3. Wealth generation. This one was particularly poorly thought out. Tourism? The amount of space dedicated to tourism would have to be so huge to offset the living costs that I don't see this contributing in any meaningful way to economic surplus. Manufacturing dangerous goods? Space ports? Who would want to live near such places? All of the possibilities offered were of small economic value. Any balance of trade would tilt massively in favor of land based economies.

4. Expulsion. How and when do you expel members of the community? Do you write a set of laws, with the more severe prescribing exile? How about people who fall behind in their financial obligations (i.e. taxation) for one reason or another (for example, someone gets sick and can't pay their bills on their salary)? That works well for those on the top, but for those at the bottom of the totem pole, it would be intolerable.

5. Government. I realize that the author is a libertarian, but this worship of the "corporate" government as some sort of panacea is really naive. A corporation is a despotic form of government. Despotism is very well suited to small communities, but still suffers from the flaws of all governments: tyranny. Anyone who has spent time dealing with corporate politics will know how much it resembles swimming in shark infested waters. Political rot builds up, and is all but impossible to remove. Psychopaths make their way to the top and rule with an iron fist, making the company financially profitable, but a nightmare for those who work there.

6. War. The author glosses over arguments of war by hand waving that it might not be as bad as with historical autonomous governments, or that "war drives away trade". Historically, this has not deterred those who bear a grudge. Furthermore, outright armed conflict is unlikely to be the norm. Far easier to simply sabotage the rival platform, since damage to a sea platform is orders of magnitude more devastating than damage to land.

7. "You can just leave if you don't like it." This always makes me laugh. Leaving is not something simple like changing washing powder brands. Leaving involves uprooting your entire life, leaving friends & family, giving up all agreements, titles and numerous other intangible benefits, and then starting over with only whatever money you have in a new place where you don't know other people. The barrier is actually quite huge, especially when the community is small. It's even worse for people who are born on the platform, but don't agree with its politics. You know, just like libertarians who are born in a country but don't like its politics. You can always just leave, right?