In Illinois the vehicle code reads. "...reasonably necessary to insure safe operation...".
In Illinois right turns are permitted after stops at traffic signals. I do not see anything unsafe about taking 2 seconds or 10 seconds for that matter, instead of the fractional seconds some impatient drivers give you before they start sounding their horns.
To answer your question is a 30 second horn blast reasonably necessary to insure safe operation of her vehicle? I wasn't there, but I did have a driver back right into me eventhough I sounded my horn for at least 5 seconds but he did not see nor hear me, 30 seconds seems an unreasonbly long time to "insure a safe operation of their motor vehicle".
In Illinois it is illegal to use the horn at any other time. Yet I hear cars marked "just married" blow their horns all the time.