Even though you're just flying a few guys (say a few acid guys, maybe an engineer who knows the toilets, just in case) out for a day or two, that's stupidly expensive. Not even just the cost of putting them on a plane or helicopter- even though you may only be paying for a few hundred man hours, you need to pay a lot to pull those guys out of whatever they were doing.

4,700 people shitting in buckets is kind of an emergency in the middle of the ocean, unfortunately. The navy is notorious for its sleep deprivation and tight schedules. Seemingly small disruptions and timewasters can lead to major problems and mistakes.

Also, it surely cannot be a good idea to keep massive amounts of acid around for non essential purposes.