I have seen exactly the same situation when arriving on that same flight from JNB. I agree with you that the greatest shame is on the passengers who behave worse than a herd of animals.
Once when something like this happened I saw a woman separated from her child, as the doors were closing, so I forced the doors open and the train could not go. The policemen who were standing watching the situation develop suddenly sprang into action and came and started yelling at me.
Things rarely go wrong at ‘Unique Airport’ but when they do, it’s badly handled.