Dry run.
Totally agree. What “disabled” person would be carrying a bag of sparklers, and just happen to leave them “BEHIND” the toilet.
Nothing coincidental about this one, IMHO.
Far more likely that it was an "Indian Reservation Fireworks Run." It's not at all uncommon for folks thereabouts to visit one of the many nearby reservations to buy fireworks.
Betcha dollars to donuts that some kid went to the can, put his fireworks down to take a pee, and forgot them there. You can bet that his family won't be making a claim on the bag....