It is to with their new saddles and the shimming that they advise people to do, I have no first hand experience with this just from what people have told me who I trust totally on saddle fitting advice and going to learn more myself this year with one of the best saddle fitters in the UK
They get you to shim things up so you are sitting on the back of the saddle right on the weakest part of the horses back like Linda suggests you do. Also the saddle is too wide for their and then shim it up to fit, I have no problem if you need to shim but it is in the way they tell you to do so and the fact that a saddle too wide can do a fair amount if damage as can narrow one, I am talking more about the english style than the western as that is all I know about as they copied the balance saddle from over here
Ok your balance points can change depending on what you are doing so what are the exact body parts are you balancing on in the saddle. I balance on just my seat bones using my core to stablize me, but with the weight going through and down my legs and if you took the horse away from me I would look like I was still standing and it is the most secure seat classic done correctly, try doing what Linda advocates and stay stood up
The saddle being fitted behind the scapula is indeed correct it is the other advice that isn't brilliant and unfortunately some saddle fitters still give you bad advice and do a bad job cos they know little themselves, hear and seen lots of things over here even worse when the saddle is twisted in some way
Also doing up the cinch as you say is sensible I am on about the english saddle they have that has come out recently not western as I have not much clue about that yet.
Hope that has made things clearer for you they are great at some stuff and Pat is at his riding but Linda mmmmnn is scary stuff what is being advocated to do when they have much followers as they do and that they are off the mark with their teaching of the seat.