Thanks for the explanation.
Regarding crime. I guess the way it's dealt with will depend on how the seastead is set up. Take a look at this research paper done by STI.
It discusses the different ways a seastead would operate from a business standpoint. Perhaps a company owns all the platforms and rents them out. Perhaps they own all the platforms and owns the businesses on the platforms. Perhaps there are smaller platforms and each business owns the platform that it's on. There are many variations, and each one will reflect a different solution for security and crime.
Let's just take one. Say it's a large company that builds the platforms, and then sells it to a real estate company who then rents out space on the platforms. Lets say the terms of the lease say that the real estate company is responsible for the safety of people on the platform. They could then hire private security to maintain that safety. If they want to have good business, the security will not be heavy-handed, but it will do a good job of preventing crime and addressing crimes if it happens.
This is not authoritarian because people are entering into voluntary interactions. The terms of the lease stipulate the security, and the businesses can choose to enter the lease or not, given those terms.
In reality, the security is a plus, however. Imagine the liability and bad reputation that the businesses themselves as well as the real estate company would suffer if it weren't a safe environment.
You're not replacing one overlord for another, because the security company is subject to the market, and if people have bad experiences with them, the businesses and the real estate company will find another company that does better business.