The assumption is because of the 95 on the username, which is a strong indicator that the author was born in 1995. It sounds like you misunderstood and thought

The assumption is because of the 95 on the username, which is a strong indicator that the author was born in 1995. It sounds like you misunderstood and thought he was merely saying that it sounds like a childish username, which he was not. If the username was crimewriter65 it would be strongly indicating that he was 46 years old.