Giving it a quick look they're doing the same thing as everyone else and handwaving away really difficult engineering problems with some back of the envelope math that only looks at one or two aspects.

Like their section on collision avoidance isn't any more sophisticated than "Starlink has a great record so far" when we're talking about a very different scale of how much mass and surface area has to be moved around in a coordinated way.

This is in effect an editorial from two postgrads, not an actual detailed workup. I don't feel like spending time going into any more effort based on that.

Saying it is equivalent to launch costs is hand waving. Their "median" scenario would involve Starship working at the lower bound of their operational goal for it.