IMHO the Chinook was bloody miles away albeit not where he was supposed to be.
Well, not really. The Chinook is still visible
inside the airport boundaries in the video frame showing NU-610 on the ground and slowing, at AvHerald. Less than half a mile @ less than 500 feet (and less than that when the decision to continue the landing was made).
Incident: Japan TransOcean B734 at Okinawa on Jun 3rd 2015, continued landing onto occupied runway despite instruction to go around
For me, this incident highlights the dangers of
assuming everything will go "right".
The controller cleared one plane to take off while another was on final approach, thinking there was adequate spacing. Which would have worked fine, assuming nothing went wrong. Unfortunately something
did go wrong (and if it hadn't been the Chinook's mistaken takeoff, it could have been a bird ingestion or some other reason for a takeoff abort.) And suddenly the "adequate spacing" was no longer there.
The landing pilot assumed he had enough space and performance to slow and avoid the aircraft stopped on the runway. And indeed he did - with maximum braking effort (from the body language of the passengers describing the landing).
But suppose this was the day the reverse gate decided to jam, delaying the start of deceleration a few seconds?
Personally: If I were the landing pilot, the moment I heard the tower call "abort takeoff", I'd have been in high alert mode, with "probable go-around" in the front of my mind. Listening hard for an acknowledgment of the call, and looking hard to find the helo, and see what the aircraft on the runway was doing. I'd have kept my options open as long as possible.
This pilot used his command authority to do what he thought was best. In the event, his decision was not disastrous. He'll have to justify his decision to two entities - those who control his license, and those who control his paycheck. Their opinions are the only ones that will count.