I'm uncomfortable with any "lynch those other hikers" mentality when, as far as I can tell, we don't even know it WAS other hikers. Balls wrote in his journal "While we hike the Gila, Beacon is going to cache food and water along our next section of CDT which is known to be dry including a 60 waterless stretch."
If someone wanted to mess with a hiker, seems like it would be pretty easy to check for water caches at each road crossing along the next stretch, then take any visible water and leave a note making it seem like it "had to be those other hikers."
I don't know that that's what happened. On the other hand I don't think we can be reasonably sure who DID take the water, and why. So while taking the water was a very bad thing to do regardless, I don't think anyone should insinuate that it was fellow hikers. It's a very small community out there and a rush to judgment might smear some very good people's reputations.
A good policy for caches is "out of sight, out of mind." At least Balls had wisely planned so they weren't down to their last option, depending on a single cache for their lives.