Many a person has done, in a flash of anger, something they later regret because its consequences are far more momentous than expected.
I am not saying that this is what happened, but a carelessly flung out arm while gesticulating could potentially cause a fall that turns fatal. Panic sets in, and unwise actions evolve from there.
Just a thought of how a seemingly harmless action, with no intent for causing injury or, worse yet, death, can escalate through pure dumb luck or poor judgment.
Sometimes people panic. They fear that whatever explanation they can offer of an event will not believed. Things grow from there. It happens to a much lesser degree in our everyday lives, and we all would love to firmly believe we wouldn't do the wrong thing instead of telling the truth, but you have to be in the situation to actually know what your actions are.
Opinion, pure and simple.