No, we don't know whether flash freezing insulin ruins the insulin. Flash freezing is not the same process as the slow freezing process in an ordinary freezer. As far as I know, no research has been done on this topic. The process described in the patent (quoted below) might also apply to modern insulin analogs, but I would not try it until research has confirmed that it works.
Current practice and regulation prohibits freezing insulin because of physical and chemical deterioration, and the consequent loss of physiological activity, which occur during the freezing process. Such prohibitions have heretofore been wise and necessary and remain so if proper freezing technique is not employed since deteriorated insulin will not effectively arrest the diabetic condition, resulting in a coma or death. It has been found, however, that if the freezing process is sufficiently rapid, the deterioration which occurs under normal freezing processes does not occur, and the insulin retains its full potency and efficacy.