He wasn’t seasoned.
In '46-'47 Mustangs were selling for $2500.
And many of those who could afford to buy them without knowledge as to how to fly them lost their lives because of engine torque on take off.
$2500....
I just happened to read the NTSB report on that one a few minutes before hitting this thread. It was the pilot's first solo in the P-51, which was a two seater. The instructor had landed with him, got out and told the tower it would be an initial solo. The pilot made a circuit, touched down and started a touch-and-go takeoff when it went on its back.
It's interesting to note that the final production P-51H was built with a much taller fin and rudder in an attempt to provide a better means of handling the torque roll problem.