And I still can't imagine why the pin was being replaced on the roll out with other aircraft in the vicinity, why on earth does, or perhaps did, the RAF allow such sloppy procedures?
Pins should only be installed when , ideally stopped, but only when circumstances allow visual confirmation of correct insertion. Period
I'll go fetch a ladder so you can get off your high horse safely.
The existence of position 2 and 3 for the SFH were not known about and neither was the possibility of initiating an ejection with anything other than a vertical pull.
The best knowledge at the time was that if you had inserted the pin then the SFH must have been safe. No visual inspection was required, why would it be? The pin wasn't believed to be capable of going anywhere else. In any event, a visual inspection of the pin when the SFH was in position 2 or 3 from the normal seated position would simply show the pin to be "correct" as looking at it from above wouldn't show the problem.