Actually, the AMA sanction has to be processed well in advance of the date of the event.

This includes the name of the CD that is charge of the event.

If on the event day the CD shows up and then leaves, there is still an AMA sanction in place, CD or not.

Just because the CD is not present, it is still an AMA sanctioned event.

It is the CD's responsibility to officiate the event, competition or not, for the entire time stated on the sanction.

Maybe some CD's don't like taking responsibility for things that sign up for....