Gee, we were wondering the same. Perhaps it's due to the fact that notwithstanding those "interim peace accords", the PLO maintains its charter to destroy Israel through armed violence.Hamas has refused to recognize Israel's right to exist or renounce violence, while the PLO has signed interim peace accords with the Jewish state. It was unclear how Hamas would be included in the PLO, given the discrepancy.
Nah! That answer would be too easy.