There's 19.2 seconds from "sound similar to touchdown" to "sound of crushing noises"
It took the crew just 2 seconds to notice "spoilers nothing" and about 6 more seconds to fully realise that they had no deceleration -- reasonable human performance.
They were left with 11 more seconds before going off the end.
Question for the AB people: What is the SOP when you realise you have no spoilers?
Perhaps reverse should not be selected before seeing spoilers deployed in order to preserve the option of taking it back up?