This is kind of what I expected to hear - I find it unfortunate that people move directly towards a professional rating before they are ready. Let me be perfectly clear about one thing - this person may have never had a panic situation prior to this event - he may have felt that he was ready - sometimes people are unaware of what will make them panic until it actually happens. I fully understand this and am in no way bashing this diver or his instructor(s) as this may have been totally unforeseen.
Now, personally, I did not even consider DM until I had been diving for five years with well over 100 dives to my credit. I had experience in cold water, warm water, low vis and high vis. I had been in situations where I had to actually rescue a panicked diver at the surface. Bottom line, I felt ready, my instructor evaluated my skills fully and felt I was ready. (he even had the other DM candidate do a buddy breathing gear exchange in the pool while swimming with me - THAT was interesting). So, yes, I was ready mentally and physically. This guy may have felt EXACTLY the same. There are too many unanswered (and most likely won't be answered here) questions to know for sure.
Some people can handle this sort of thing from day one - some never get there even after 300 dives. You won't know until you try - but it appears to me - and again, I am not certain, so please keep the flamethrowers stowed - that this guy was waiting for the minimums so he could start DM class. Minimums are just that - absolute mins for attempting the class - they are NOT a substitute for appropriate experience and actual ability.
I do hope this guy gets back in the water and can learn from the experience. I actually hope he makes it to DM - he has a GREAT experience to tell future students from the been there, done that perspective. As long as he can get past the panic episode and learn from it - perhaps re-evaluate his self-rescue skills and expand on them - he could make a superb DM. I hope it works out for him.