The report says the black box reports the fuel cutoff switches being activated. That doesn't necessarily mean that either of the two pilots activated them, it just means that the fly-by-wire system reacted to a fuel cutoff event.
"The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cutoff.
In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff.
The other pilot responded that he did not do so."
It does:
1. Those switches have physical interlocks and cannot be manipulated by any computer system.
2. The flight data recorder is measuring the position of the switches; they aren't inferring the position from some system state. There's a "position of this switch" channel.
The switches were physically moved in the cockpit, that's basically ground truth. The question now is who and why.
The fact that your car's engine stops doesn't mean you turned the ignition switch off. Anyone who has had to troubleshoot a car with intermitent electrical faults knows that.
The switches physically moved, and there is no motor to actuate them without physical intervention.