I think what is wrong with it is that you can not do it and maintain ski to snow contact without the skis going in two different directions. I'm standing here, in my kitchen, going back and forth between my sink and the island and the only way I can feel myself tip the inside ski before the outside ski and not go into divergence is to lift my inside foot off the ground. We're talking about a ski that, in theory, should have the majority of the weight on it and through transition we redistribute that weight to the new outside ski. I often have much of that weight out there before my tips reach the fall line, but then my skis move simultaneously. Can you describe to us how you imagine it?
I love that you're trying it out at home
The ski does not have to be in the air, just lightened. Change which leg you're bearing the load. Its a simple matter of muscle control. A lightened ski is not going to diverge.
Unweighting can be gradual or nearly instantaneous. I do not think a weighted release is always necessary. I also don't think that even a weighted release needs to have the majority of your weight on the downhill ski, you can absolutely lighten it substantially while you release it. In fact this very thing helps to topple the CoM across into the new turn.
I would also suggest that by the time you're past flat and on the inside edges, the weight transfer to the new outside ski should be largely completed. Or certainly could be...
Also I would like to point out that we are really talking about very microscopic look at things here. If you initiate the turn by tipping the downhill ski, the ski tipping will pull your knee into the new turn (something you said you focus on ), the knee is attached to the femur which is attached to the hip. So tipping the downhill ski pulls the hip that direction. On the other half of the body your hip is attached to the other leg which also gets pulled that direction. So in many ways, tipping the inside ski first and primarily, will cause the new outside ski to tip nearly simultaneously without a great deal of effort to avoid it. Sometimes you can achieve a so called O-frame with your legs because the new inside leg is leading the effort.
There are advantages to this.... I don't see disadvantages and I don't think this means divergence.
Conversely, some harm can come from trying to be aggressive with direct outside ski tipping onto the BTE. In many ways that is the only way to truly, even at a microscopic level, tip both skis simultaneously.