If the Erekat wishes to deprives the Palestinian residents of the PA of law and order, then there isn't any particular reason why Israel should rush in to restore it. The PA/PLO can not pretend to be a state in being and then make claims that they can just pick up and abandon their effective control of the territory they claim for their state. That is completely unreasonable. The assumption is that were they to do so Israel would be forced to pick up the bag. Fortunately as in the case of Gaza there is always the alternative of simply refusing to accept authority. Israel is under no obligation to reoccupy territory that it has withdrawn from...
Syrian group says Nusra abducts its leader, in blow to U.S. plan (Reuters)
from the article: Erekat: Palestinian Authority cannot exist without independent state