It would seem to me that controlled evacuation of at least some passengers should have been considered sooner rather than later.
Reports suggest that the location was not that remote, and that taxis or buses could have been used.
No need to evacuate everyone, some might prefer to remain on the train, which will after all EVENTUALLY go somwhere.
Each person evacuated renders the enviroment more acceptable for those remaining. The vehicles evacuating some passengers could bring supplies of water, snacks, toilet paper, and anything else needed.
Some reports state "no air conditioning" but the videos posted elswhere show normal lighting in use which suggests that the front power car was running and providing ETS for air conditioning and other purposes.
It seems probable that the air conditioning was defective anyway in one or more more vehicles, this would rapidly become uncomfortable even on a mild day.
This also suggests to me the need for partial evacuation, those standing for hours in hot and humid conditions would have good reason to complain if not evacuated.
Those seated in air conditioned vehicles might be more willing to wait, and again, each person from a coach with functioning air conditioning who decides to evacuate, is one more space in relative comfort for those who decide to wait.
If I had been on the train and forced to stand in overheated conditions for many hours, I would be complaining long and hard.
If I had been seated for 6 hours in airconditioned surroundings, and provided with snacks and drinks, I would have waited it out with only a modest moan.
This is the sort of announcement that I would like to hear
"Ladies and gentlemen, I apologise for the delay, rectifying the fault is proving much more challenging than expected and the delay is expected to be some hours. We have arranged for a large number of taxis and a couple of buses at the nearest road access, to access these you will need to walk several hundred metres over rough ground, staff will help you as far as possible. Alternatively you may remain on board, supplies are en route, and conditions should be much more comfortable once some people have left"