I certainly have seen with my own eyes a train door "ruthlessly separate a child from his parent". I don't think I've ever seen an adult so distraught. I have also seen with my own eyes a lift door close on the head of an extremely elderly man. These things do happen.
It’s not obvious to me that the train pulling away was the point here. It is merely a meditation on the fact that machines are “absolutely incorruptible”, so if we’re talking about the same thing, it is a tangential fact if some human did or did not pull the cord.
If we are talking about how human intervention softens the incorruptibility of machines, then what you wrote supports that point.
If we are talking about if machines are inherently good or evil, then we have somewhere changed the topic in the middle.