Read this and then tell me why the Palestinians should trust the government of Israel. It's from the Israeli Jewish human rights organization, Gush Shalom.

http://www.spectacle.org/0601/israel.html

According to Yitzhak Rabin, Arafat and the PLO were willing to work with him in stopping terrorism. (This was during the time when the Palestinians still had hope because they thought the Oslo agreement was going to result in their independence and a sovereign state for them)...

"In the last two years, not one Israeli has been killed by PLO terrorism," Rabin said."
http://www.jonathanpollard.org/1995/100595.htm

During the Israeli incursions into the occupied territories in spring of 2002, the IDF destroyed most of the PA civil infrastructure, including police and other security forces. So I think it's reasonable to suppose that Arafat doesn't have the physical means to do what you think he ought to do, especially considering the fact that he is being completely imprisoned within his compound by the IDF. But personally, I don't see why he should be expected to provide security for an occupying force. The government of Israel should remove all of its forces from the West Bank, Gaza, and East Jerusalem, and defend its border, the Green Line, from the Israeli side.