Re. minimum age required to become a citizen. Here's a link
Immigration Law
Eligibility Requirements
2. Minimum age of 18 years. However, many children may become automatic citizens upon naturalization of their parents. See information regarding Child Citizenship Act above.
So if Laurean became a US citizen at 15, it must have been because his parents became naturalized.
I read that there is as much “if’s” there as there is in the FBI posts about whether he is legal are not. But it does say that he would have had to enter the country legally for the Child act to apply.