What happens if the claimant of lineage provides proof for the paternity of the non-communicative child held as a slave?

Primary text

If proof of paternity is presented, lineage is established, but the judgment of slavery over the child is not necessarily removed. This is permissible if the father could lawfully have a slave son, such as by marrying a slave woman or if the child was captured and the father later converted to Islam. However, a specific narration holds that if the father is Arab, he cannot lawfully enslave his offspring; this is also an old view of Imam Shafi'i.