AJK is not and never has been 99% Punjabi, no one calls themselves Punjabi. The people of AJK fought the Sikh Punjabi empire, Punjab in Pakistan did not and allied with it.
I will agree with you there is some misuse of the Kashmiri identity, as that the people, around 85% are descended from tribes that migrated from Punjab hundreds of years ago. However, parallels can be draw with Afghanistan, where traditionally being Afghan meant you were Pashtun, however that doesn't stop or put off Tajiks which is a different ethnicity calling themselves Afghan.
Again I'll agree there is no 'oppression' as such, but the people of AJK have suffered and it's them who are the first to be shaheed whenever the Indian army opens up with heavy guns. There has been literally hundreds of deaths due to cross border fire. Excluding yourself I find it erroneous that someone sitting in a housing colony in Lahore and Karachi can be tapping out on their keyboard on how the people are traitors and should be crushed, when they themselves haven't seen a single day of suffering.
As for the stripping away of rights, we don't know who holds the seats and they have been used for political leverage. I have no issue with the seats and they should be kept for the ancestors of those who migrated. So where are all the Ganis, Bhatts, Lones, Gilanis, Mirs etc?
The figure for Lahore is more or less correct and comes from the 2017 census.