The study you linked is evidence that prior infection reduces the rate of reinfection. Yes, this would be surprising if it were not true.
Your prior claim was that prior infection is equivalent to or superior to vaccination (i.e. relying on prior infection was not "heightened risk"). That was, and remains, completely false.
Your prior claim was that prior infection is equivalent to or superior to vaccination (i.e. relying on prior infection was not "heightened risk"). That was, and remains, completely false.