Yeah, sort of. It could be that in some cases the politically correct standard happens to be right, but the fact that something is politically incorrect doesn't in itself mean that it's wrong. I wouldn't accept that you shouldn't say something just because it's politically incorrect.
You say that we "must be ready for the consequences" of being politically incorrect, what do you mean by that?
If you go against the norm of political correctness where it isn't warranted, be ready for the consequences.
It is politically correct to allow extra time for a senior to walk through a door way.
It is politically incorrect to push them aside. Not suggesting you'd do either. But someone who "rejects" political correctness with a weird brain might think, "I'm tired of waiting for seniors. Pushing them out of my way is what I think is appropriate, and that's what I'll do". In that case, the consequence is getting charged with assault or beaten up by an onlooker for doing something politically and morally incorrect.
So what I'm saying, is that when you said "why I must reject political correctness" might be too simplistic of a statement. It's a very touchy subject, as you see, one of us just got blasted by @shekelemberg for even "talking" about politically incorrect examples when it was only used for illustrating a point.
P.S. There are some gang-bangers who think it's funny to watch a senior get flung aside and get thrown to the ground. So it happens.
I suppose it is true that societies over time develop normative standards for appropriate behaviour, and such standards are enforced through social disapproval towards those that don't follow the rules. The real reason for not pushing seniors out of the way is that it would be cruel and disrespectful, but social enforcement of such standards could well improve the behaviour of people who would be too self-absorbed to care. So maybe that's not such a bad thing.
I think what I'm really trying to stress is that we shouldn't substitute political correctness for actual reasons. Rather than teaching people "don't do that because we disapprove" we should try to teach them to actually have concern for others, if at all possible.
I can see your point though, my statement could be misleading.