Please don't get me wrong. He was put in a very difficult position, and the instruction would have been a "surprise" to anyone. The point is that your 747 pilot would have dealt with it, the poor boy couldn't, which returns us to the question, was he allowed to go solo too early ?
Magp1e,
Quite obviously, the average 747 captain would have flown many thousands of hours and if he couldn't cope with an ATC instruction he would have known from experience gleaned and would have told ATC so. If not he had no business sitting in either seat! The point is, would a 747 pilot ever be asked to complete this type of manouevre for another, faster, aircraft on finals, behind? If not, what's the difference? I very much doubt it; the second aircraft would have been given speed control, or given extra track miles, or a combination of both, which could also have been applied in the case of this accident.
As I previously stated, the average student on a second solo has very little spare capacity to cope with the unexpected and can easily get distracted from the basics of handling the aircraft. (Ask the average 747 captain, who would have once been in that position himself)! It's for this reason that the RAF has, for many years, had a Duty Instructor in the tower at flying training bases, to act as an ATC liaison and to be immediately on hand to advise solo students if necessary.
It appears that this young chap was sent solo in accordance with the normal CAA PPL syllabus and was reportedly a good student, so the answer to your question "was he allowed to go solo too early?" would appear to be NO.