The 'bootful of rudder' is not anything that a pilot has learned to help in this situation but it is an example of why it is necessary to supervise adequately an inexperienced pilot on type and to provide continuity in training.
Whatever the symantics of 'airworthiness' definitions, this is a simple case of failure to provide both supervision and continuity of training.
The buck stops well above those who perished in this tragic accident.