Well, there's "occupied" and then there's "occupied". As I'm sure you know better than I, a runway is "occupied", whether waiting at the numbers for takeoff clearance or clearing the departure end threshold. I'm not sure about that latter point, the aircraft may to still have to be physically in contact with the runway surface, but that is how I recall it having been explained to me. Then again, there's "short final" and then there is "short final".
Here's a link to the AvHerald article:
Incident: United B78X at Paris on Jul 20th 2020, cleared to land on wrong runway, ATC error saved by Easyjet
I don't know, but it sounds pretty serious to me ... but not as serious as the Air Canada 'Bus lining up to land on the full (of taxiing/stopped aircraft) taxiway at SFO.