Useless paper. Measuring arbitrary antibody levels. The antibody levels produced by natural exposure could be sufficient to protect against hospitalization, and the additional vaccine dose could be unnecessary. Also, 21-day follow up (laughable).
Show me some real-world data of previously infected individuals getting severe reinfections at significantly higher rates than the fully vaccinated. That's the metric needed to make your claim and those data have not been produced. Also, the staying power of the vaccine is already in question BY ITS OWN MANUFACTURER just via the prospect of boosters. They admit implicitly that the immunity their drug produces does not last.
> circulating antibody levels alone are not definitive measures of immune status
This is well established in the literature.
The paper you have cited absolutely does not support the claim that the "vaccine is more effective than antibodies from a previous infection".