When this first broke, I speculated that possibly a mullah may have been in attendance at the speech by this oppressive cleric.
You know that all kinds of eyes were watching mullahs scramble back up into their penthouses when this happened.
Taking a headcount and status check on 86 of them takes time, if you are suspicious of your comm channels. This may have been an extraordinary intel gathering event, regardless of the culprit.
Reports from regime are saying that the reported dead cleric is ok, and that the explosion was a result of left over ordinance from a war week memorial celebration