The precision and speed actually makes it look like a planned maneuver. "Hmm, today I will trap myself in a box and fall of a table. That seems like a reasonable thing to do"
His plan was to go all Solid Snake on those keys by hiding in the box and sneaking up on it all stealthy like. Sadly he was foiled by an impossible to predict combination of box transparency, disorientation and gravity.
That "oh shit" screech as he went down 🤣