I was wondering that myself about the "pressure bump" and the amount of cord taken, one could only wonder if he manipulated the stairs causing this, seems the crew would not take note of anything else beyond that point, you would think with the stairs dangling like that all the way to Reno the gauges would have tripped again somewhere with turbulence?
He could have controlled pressure bumps if he knew about them ahead of time. Cord would have been very useful for that. The stairs dangling would not have caused significant guage reaction.
He could cause a bump by wedging something at the end of the cord between one or both struts and the wall of the stairs while down on the stairs, then jerking the something out from the top of the stairs using the cord. The "something" could even be a big knot of cord. He could then have avoided making a bump when he actually jumped by leaving something wedged between the struts and walls. Whatever was wedged in could have vibrated out at any time later.
All we need is to get the flight data recorder data, then check the whole route.