ET, genuinely, do you not realise that just sometimes, occasionally luckily, people DO come into teaching for more sinister reasons than a love of education and children?
I had a primary school teacher who sexually molested us (luckily in a non penetrative way) throughout Year 6. Looking back it was horrendous but at the time we would never have questioned it because he was our teacher.
Now, we have moved on from those times, and before anyone jumps down my throat I am absolutely NOT stating that this teacher is anything LIKE that horrible man, but it's still dangerous territory. Once you start from this assumption that the child is wrong, the teacher is right, the teacher cannot be questioned, the child is at fault, you're basically making assumptions, and you should not do that with vulnerable (which children are due to their age) people.
Most people are reasonable. 'Gosh, you know, I'm sorry, he asked for a drink, I asked him to hold on as the girls were talking and then it slipped my mind!' is not deliberate - but 'no, you're not having a drink because you had the audacity to forget your bag!' is.
It doesn't matter how improbable or stupid or unlikely YOU think the teachers action was. Misunderstandings between child and teacher will happen and mostly can be explained but no one should have to accept someone in a position of authority over them using that authority for discomfort. That's the bottom line.