Rear wheel drifting right during jumps

Well Jr. crashed hard and I was right behind himduring the jump. He came up at a double about 50' he changed lines coming from left to right but seemed to straighten out before actually hitting the face. Immediately as he left the face the rear wheel started to drift to the right and when he landed he was about 45º to the track and high sided. Now I've seen him bring the wheel around like that before several times and I sorta thought he was trying to whip it on purpose. During this particular jump I thought the rear wheel drifting was due to the change of lines and maybe some momentum being carried to the right.
Someone suggested that the gyroscopic effect of the wheel could cause this if the rider was to stay on the throttle during the jump? Could this be a cause?

The rider is a 9 year old 72lbs rider on a 65

bummer so I'm not homing in on a route cause. I'll have the suspension guru here watch him ride and see what he thinks. thanks guys.

we're riding the ktm 65. I thought this might be a one time thing but i have seen him drift right many times. this is the second wreck where he landed sideways and highsided. He's usually good with pinching the tank but I have not paid attention to while he's jumping. He can whip the rear on command and does so sometimes and he can birng it back. I asked it he was trying to whip and he said no. We'll have to see when he comes back. I'm going to video some jumps from the side and behind to see if we can spot anything. It might take some time cause I know he's going to be skittish for a while. Its one of those things I'll just have to let him do when he's ready to do the jumps again.
It was the last moto of the day and the track was packed hard. He might have gotten some wheelspin. He did the jump most of the day in 3rd and was coming up about 1 foot short. He tried it the last 2 times in 4th and was still accelerating when he left the face. New tire 14psi. Stock spring with about 3" of sag.
As far as the suspensions we've ridden the KX and immediateley we needed suspension. We also have a Cobra DC65. Its got the motor but we're still sorting the front suspension. He rides the KTM because he feels most comfortable on it. We barely had to change anything suspension wise. Just fork oil weight.

Thanks guys.