Regarding whether he would fall over or not with the leg movement I've drawn, that would depend entirely upon how fast he is going, the radius of the turn, how much pressure ("balance") he sustains on that inside foot, and what other compensating movements he might or might not make with his arms and upper body. I suspect that, all else being equal--and in particular given the relatively low outside ski edge angle that would both tend to elongate the turn radius if carving, and minimize the outside ski's grip (edge hold), making carving unlikely, that you just might be right. But with proper alignment and other adjustments, all else would most certainly not be equal!
Edit--ahh, I see that you have added another image while I was composing this post. The red lines on the final (largest) frame would appear to support the misalignment argument, as they illustrate the angle the shin would need to be if it were to form a 90 degree angle to the ski base. The lines on the first frame may be relevant too, but the camera angle there makes it even more difficult to accurately estimate "lateral shin angle." Nevertheless, if you are correct that the shin and ski form more closely a right angle in that frame where the ski has minimal pressure on it, but an acute angle in the final frame where the ski is highly pressured, it supports the thought that he may have a lot of slop and play in his binding/boot interface. With wide skis on harder snow, pressure on the edge applies substantial torque which tends to fight against the skier's efforts to tip the ski on edge. Worn boot soles, play in the bindings, or even too loose or too laterally soft boot cuffs will make the problem worse--and any of these could be happening in this photo-sequence. On the other hand, the fact that the inside ski also appears to show a similar "underedged" alignment--even with some pressure on the little toe edge--does not support the "loose connection" possibility.
All of these things would be worth investigating, Alex.