He means your getting your hips into some of the movements a bit.
I have done very similar pushups to this. It is very difficult not too , even when you don't raise the legs.
If you don't jump with your legs at all it is stricter.
The only things I would say is that if you don't lift your legs too and you can get very good height, it is very easy to hyper extend your back .
IMO they are still very useful variations. I don't see the need for the negativity.
I am struggling to think of better upper body plyos, we a rapid amortisation period (if that what it is called).
You could try and blast up as soon as you fall, but take a few sessions to do it. It is surprising how much more difficult it is.