You’re told when you buy a ticket to prepare for this sort of event - it’s happened before. So anyone who’s actually on their shit will have enough food, water, etc to wait for it to dry out and leave normally. They even explicitly advise bringing a bucket to turn into a makeshift toilet if something like this happens and shuts down the porta potties.

That said, I’d bet a sizable fraction of the attendees are completely unprepared or dependent on others to get them ready. Probably people will share extra supplies with them. Maybe this entire event will expose just how commercialized it’s gotten.