What does the 12% figure mean exactly? Is the area on the east side of the wall only 12% of something larger, or does the wall take in 12% of the pre 1967 borders?
Palestinians who make up half of the population on historic Palestine will be stuck behind Apartheid walls and fences on 12% of historic Palestines land.
I didn't catch that. I think he's referring to the fact that the West Bank and Gaza are only 12% of the British Mandate, which included what are now Israel and Jordan. Don't forget that along with the destruction of Israel, a formal goal of the PLO is reunification with Jordan. Just because King Hussein defeated them in 70-71 doesn't mean they've abandoned that objective.
The 12% is based on this, if you figure Jordan=80% and the West Bank & Gaza=8%: