Did it ever occur to you that she is WORKING on those things? WORKING on those things implies that they are not perfect and that it's a work in progress. Remmer is an introverted horse by nature, so dressage has little purpose to him and the fact that he's offering that to her is awesome...and she doesn't have to use spurs to keep him going. I've seen with my own eyes Remmer get VERY suspended in his gaits and it's just beautiful.
I actually have a friend who took a clinic with Walter once. She said she didn't like him AT ALL because he was critical and not that gentle with the riders. However, as much as I love my friend dearly, she is very stiff and quite hard on her horse's mouth, yet she doesn't think so....so I don't believe you that Walter won't be "firm" about things at times. And I don't think he would lie about Linda doing nice things with her horse ;)
As far as Linda being stiff......omg, she is one of the least stiff riders I have ever seen. And Remmer is a VERY honest horse who will do *something* if he doesn't like something...and a stiff rider is one thing he does not tolorate. She was flowing with his motion, not bouncy, fluid, and Remmer was nice and quiet.
Quite honestly I think you're just pulling at things to pick on. Do you not want Linda to be successful with Walter and in dressage? Hmmm...