I am not going to assign blame to anyone, we'll never know concretely how it all started and went down.
But, I do want to point out that relying on information from any of the runners is foolish. Eye witnesses are historically terrible at getting details correct. The same is true here. They may say they felt this or that, but in reality what they perceive to have happened may not have been true. Montano thought she was in lane three and she wasn't. That is an example of what I'm talking about.
Anyone that has run the 800 meters probably has a story where they finished the race, looked down and saw blood and didn't realize until just then that, "Hey I must've been spiked". I can't tell you how many times I've been spiked and didn't feel it in the moment.
My point is the whole thing happened so fast that to ask the runners what happened and expect factual answers from their perceptions is foolish.