The story reported that the men became sick. That's what happens if you drink water stored in a cactus. You can get some moisture from cactus fruit and all cactus fruit is edible, though all do not taste good. However, drinking the juice on an empty stomach often caused diarrhea and that will further dehydrate you.
Similarly one may ask, can a cactus hurt you?
Whether they find you in the wilderness or in the botanic garden, cactus spines can hurt -- and the little hairy kind called glochids can actually pose a risk to your health if you aren't careful. There are two basic kinds of cactus spines.
Can a cactus be poisonous?
There's no significantly toxic cactus that my Google could find, and certainly no "poisonous" cacti, though pretty much any substance can be toxic if you consume enough of it. Some sources claim that all cactus fruit is edible, albeit some may be tastier than others.
Do the spines on a cactus grow back?
Cactus spines grow from specialized regions, called areoles or spine cushions. Areoles occur along the part of the cactus known as the stem, which can be paddle-shaped, round, cylindrical, columnar or leaflike. Areoles also give rise to new branches and flowers. If an areole's spines are removed, they won't grow back.