So what was ATC's role in this (if there was a "this?").
Was the crew advised of the obstruction (outside of seeing it with their own eyes?). Were they cleared to land?
If cleared to land, it becomes a judgement call, not a legal question.
A plane blocking 1000 meters of a 3000m runway is no different than a 2000m runway with a plane (or hangar, or ocean) parked off the end. You check the numbers, procedures, and your experience, and decide if 2000 meters is enough. (Adjust numbers as needed if we ever find out the real situation).