In my view, you are correct. I think a loose grip and a passive wrist are the way to go.
But, I do think it is OK to work on a WW follow-thru. For WW, the forearm pronates a bit and keeps the palm facing out toward the target longer. No wrist roll here either.
I strongly feel that you should never ever try to roll the racket face over the top of the ball. This is FH suicide and will lead to inconsistency and smothering the ball.
I also don't think you should try to go into a WW pronation before contact either instead I think you should be hitting thru contact when the pronation begins. Some advocate starting the pronation before contact to pull the racket face up the back of the ball.
To me the keys are loose grip, wrist lays back either during the backswing or when forward swing begins, swing path is up-thru-and-across with some extension thru contact, and then let the forearm roll into WW follow-thru.