* The government is paying claims for people who are 150 years old.
* The database is using 150 year olds as a sentinel value for a missing data.
Given that the people making the claims for the former are reportedly young people (who thus have less experience with the quality of data in actual databases), who are outsiders and thus have not had training on the actual data entry procedures for the database in question, I find it extremely plausible that they made a search term for old claimants, claimed it as clear fraud, and never realized (or even bothered to ask) that it could just be a sentinel value. Especially given Musk's history of contempt for experts who tell him he's wrong, I don't think Musk's explanation that it's fraud holds up to any scrutiny, even given a lack of knowledge of the particulars of the database in question.