Doesn't seem awfully unprepared to me... He was planning on an easy 1 day hike, and took most of the gear necessary for double that if need be.
Also, an experienced hiker knows that if you drink half your water but you aren't yet halfway done the trail, you should turn around and go back. You can estimate this based on elapsed time if necessary.
37+ degrees C though I feel I would need or at least want far more than just 3-4 Liters of water! Far more than a machete on a day like that anyway.
I am not that experienced a hiker though to be fair.