Do they consider the non-locking of the landing gear an incident?
Yeppers...even if all parties land safely...there is always the question of equipment failure or weather conditions (wind shear, etc.). It's only prudent to check out each incident, no matter what the aircraft.
I spent some employment time at a LARGE aircraft manufacturer in the Seattle area... ;)
Better believe it! That is a major malfunction which could have resulted in a severe accident. As for the brave guys who SOLVED THE PROBLEM..., I doubt seriously that they will be cited for anything (nor will the pilot). It is necessary to document the incident and determine its cause...
Been there..., had that type of "incident" and though the problem was not resolved in such a dramatic fashion, I was greeted by several officials with paperwork to complete (and examine my credentials closely)...