My "guess" is that he was asked to submit his letter of resignation. I would assume he is a sacrifice or that it was done as part of a "deal" to assuage or divert any prosecution. It may not stop any personal (civil) case, but the defense in that case would argue from the standpoint that the spectators were in a restricted area.
I seem to remember reading about new guidelines, including arresting those who violate the restricted areas, as suggested by the coroners report. One surmises there will be a stronger police presence next year.