This summary is not the rule. The rule text controls.
When someone dies and one of their heirs or the people named in their will can't be found or located, the court steps in to protect that missing person's interests. If the court sees from the case records, or if someone involved in the case proves it, that an heir or beneficiary is missing (called an "absentee"), the court will appoint a lawyer to represent that missing person.
This applies whether the missing person would inherit because there was no will (making them an heir) or because they were named in a will (making them a legatee). It also covers people who would normally inherit under the law even if a will exists. The key requirement is that there must be a real need for someone to represent this missing person's interests in the case.
This rule exists to make sure that missing heirs or beneficiaries aren't left without a voice when property or money is being distributed after someone dies. The court-appointed lawyer will look out for the absent person's legal rights during the process, even though that person isn't there to speak for themselves.