It is strange, i agree. I guess having given a fair amount of instruction and examples of the start procedure, this instructor was happy that he had did not need to be present, as he expected the student to complete the start successfully. IMO an reasonable expectation, given the experience of the student. in this case he was wrong, it happens. He must still take responsibility for the damage, and thus must the FTO as his employers. The student was not liable in the slightest, as he is not qualified to take the responsibility himself.