And what race did Zaynar get his 168 in, EC1? A race over 21f in bottomless ground, that's where.
Just because a horse is given a rating, doesn't mean that it can or will run to it every time. Trip, ground, well-being, track, stable form - all of these factors need to be taken into consideration. If all criteria are met, then a horse is potentially capable of running to it's mark. If they aren't met, then a horse may find it tough.
IMO, yes - the handicapper got it wrong with his 168. That rating is the stamp of a horse with Champion Hurdle winning class, not one of a horse who gets turned over at 1/14 in a 2m race at Kelso. The error is only further compounded when you buy the theory that the Champion Hurdle provided a set of circumstances where Zaynar could run up to his very best.
Your interpretation is far too simplistic, and your apparent belief in the infallability of the Official Handicapper somewhat eye-watering, I have to say.