It’s both, if I understand your question. Having covid gives some resistance that declines over time (intentionally vague phrasing since research on this is ongoing) so recovered cases have less need for a vaccine and from a public health perspective offer less benefit than vaccinating an immunonaive person, if you can only choose one. In addition, giving people with strong immunity even more doses exposes them to needless risk, so recovered cases get only one.
It’s both, if I understand your question. Having covid gives some resistance that declines over time (intentionally vague phrasing since research on this is ongoing) so recovered cases have less need for a vaccine and from a public health perspective offer less benefit than vaccinating an immunonaive person, if you can only choose one. In addition, giving people with strong immunity even more doses exposes them to needless risk, so recovered cases get only one.