A friend of mine once told me a story about negotiations between Russia and Lithuania. I have no idea whether this tale is genuine or apocryphal, but either way, it is illustrative.
One time when the Russians and Lithuanians sought to end one of their wars, they brought delegations to meet for negotiations. To prevent any language problems during the negotiations, each side sent a Jew from their delegation so that the negotiations could be conducted in Yiddish. After one of the sessions, the Russian Jew returned to his delegation and one of his comrades asked what the Lithuanians want. The Russian Jew responded that it was not worth discussing, they wanted all the land where the Jews prayed according to the Lithuanian rite. His comrade said that that sounded reasonable. The Jew answered, "You don't understand. They want Moscow!"
Such is how the the Palestinian national movement (PNM) negotiates. The PNM makes demands that sound reasonable to someone without an insider's understanding, but to anyone with fundamental knowledge of what's inside, demonstrate a clear demand to take everything.
A slight twist on the Lithuanian negotiating strategy is that Abbas knows that Israel can see through his veil of reasonableness as readily as any Russian Jew and thus is as unlikely to meet his demands as Russia is to withdraw from Moscow. However, his strategy is to present his demands to an international audience that knows the situation the way the typical Russian non-Jew knew Russian Jewry, and has no desire to know any more, and thus see his demands as reasonable. Thus, when they see Israel rejecting demands that they see as reasonable, they open themselves up to PNM suggestions that if "reasonableness" would not convince Israel, BDS and diplomatic isolation should be deployed to help Israel see reason.