If the Captain were controlling throttles, it for some reason he could contort his wrist to accidentally open the red cutoff switch guards, the switches themselves move in the opposite direction of the pivot of the switch guard. And to have that happen to both switches — one second apart. That would be astronomically (not to mention anatomically) improbable: you can’t have your hand on the throttle and also be dragging your arm on the switches unless the pilot has an extra elbow.
Further more, the 787 has auto throttles, at takeoff the pilot advances the throttles to N1, then all the way through climb out the auto throttles control the throttle unless manually disengaged.
Also a “bumpy runway” wouldn’t do anything because if those switches were activated on the roll out, the engines would shut down almost immediately: that’s the point of those switches to kill fuel flow immediately not minutes later.
And no there isn’t a report of the safety locks not working properly on the 787. The report to which you are referring was in 2018 and that was an issue with a very few 737 switches that were improperly installed. The switches didn’t fail after use, they were bad at install time. Exceedingly unlikely that a 787 was flying for 12 years with faulty switches. (Notwithstanding the fact they they are completely different part numbers.)
The 787 that crashed had been in service since 2013 which means if that were a problem in that plane, however unlikely, with hundreds of thousands of flight hours, inspections, and the 2018 Airworthiness Bulletin — that problem would have been detected and corrected years ago.
Secondly, while the FO was flying the airplane and thus would have control of the throttles during rollout, the captain would certainly have his hand beneath the throttles in an observer position during at least part of the takeoff. And during takeoff, procedure would have the captain take over control of the throttle levers until rotation while the FO handled the yoke with both hands.
blancolirio[0] has two excellent video examples of 787 takeoffs within the cockpit showing FO-pilot takeoffs and both officers' actions during takeoff.
Page 10 of the Air India preliminary report[1] shows a picture of the fuel cutoff switches -- clearly labeled "FUEL CONTROL" with "RUN" in the up position and "CUTOFF" in the down position -- directly beneath the throttle levers.
[0] https://www.youtube.com/watch?v=wA_UZeHZwSw [1] https://aaib.gov.in/What's%20New%20Assets/Preliminary%20Repo...
I personally had some teachers apply this 10 or so years ago, and I assume the idea existed prior to them. Though, I'm not sure exactly what age range this would work best with.
From what I can tell, this is mostly a parent-led thing, well supported by overworked teachers who are more than willing to avoid even more work grading out-of-school assignments.