You’re looking at a two year old quarter horse who is base narrow in the hind end, pretty much exactly like figure e) here:
Any chance this will correct itself even a bit with age? Horse would be used for speed events and cattle sorting - not national level but hoping to do very well in club shows and obviously I want the horse to stay sound. Horse is affordable and excellent shape otherwise, very well bred with proven lines… Avoid or go for it? No experience personally with this default and my initial instinct is to avoid but hey, I don’t know everything.